If you understand focus it kinda drops into place.

Infinity focus is when the lens is at its closest to the lens, beyond infinity things get fuzzy again. Iif you want to focus nearer then the lens moves further away if you want to do macro its much further away. If you think of the lens as a movie projector and your sensor as the screen if the projector is further away from the screen the image circle of the lens is bigger and so the size of your subject is bigger too on the sensor.

The relationship between the position of the lens and the focus distance is logarithmic which makes the math hard except in some simple cases.

but the logs for focus distance in factors of 10

0.1 10x
0.01 100x
0.001 1000x
0.0001 10,000x

so for an 80mm lens to focus at 800mm the lens needs to be 88mm from the sensor (logically if not physically) a helicoid to move the lens out 8mm is pretty easy to build into a lens.

for a 100x focal length its just 1% of the focal length or 0.8mm for this 80mm lens
a 1000x focal length just 0.1% of the focal length or 0.08mm for us thats pretty much infinity at 10,000 x focal length you cant really move the lens much closer than that 0.08mm at a 1000x true infinity would be infinitely small, so in practice infinity is somewhere between 100 and 1000x focal length
Focusing closer the movement gets very large as you come in closer than around 10x and macro lenses will be moving lens elements to avoid the extreme physical movement, lets stop at simple lenses :)

so for a camera and lens the distance between the back of the lens optically is split between the lens and the body.
The camera's flange focal distance stays constant and so that is deducted from the lens for any given system.

when it comes to adapting lenses between systems the adapter has to bridge the gap between the flange focal distance of the new camera body and the distance the lens was designed to be from the sensor in the lenses native system.

because mirrorless cameras have a short flange focal length maybe 19mm and a lens designed for a SLR is designed to sit in front of a mirror box
Canon Eos is 44mm pentax k / m42 46.x Nikon 47mm its easy to adapt lenses to mirror less cameras. At least physically and as long as you can adjust aperture and focus manually it works, with converting between slr type systems it gets harder.

Canon is the shortest at 44mm so an adapter 2 or 3 mm thick is doable. Nikon being the longest has most problems to fit a canon eos lens to a nikon would require the lens to sit inside the nikon flange in order to get infinity focus. And it still needs to avoid hitting that swinging mirror , this isn't possible. On the other hand if you don't need infinity focus, you might adapt a lens designed for a shorter system for macro maybe on the longer system.

Adaptall lens had interchangeable lens mounts so the actual lens could be swopped between systems provided you had a compatible mount.

Image circle on these old slr lenses was made big enough to cover a 35mm frame when adapted to an aps or m43 frame that circle is the same size but the sensor is smaller which is why you get crop factors of 1.5 or 1.6 depending on system 2x on m43 systems.

The metabones speed booster adapters basically shrink the lens image circle concentrating the light, which effectively makes the lens faster and closer to its original angle of view. Teleconverters do the opposite and spread the image circle wider the density of light is less and the angle of view narrower.

It's possible to make a teleconverter which mates two camera systems and puts the lens at the right distance optically, usually iq is worse the lens is gathering less light and is slower. Because the image is so much smaller at the sensor the enlargement to a given size is increased and that tends to bring out the worst in a lens.

So while its counter intuitive you tend to need better quality lenses the smaller the sensor on a camera (up to a point) Because our eyes have limited resolution as long as the junky stuff is smaller than our resolution the image looks fine.

The issue with FD lenses is the "42mm flange focal distance of the FD mount is shorter than that of most other lens mounts" (from wiki). For an adapter needed for an FD lens, the first issue the adapter must address is moving the back of the lens close enough to the sensor (or further away) that the lens will focus, and preferably, retain the ability to focus to infinity. The EF lens mount for EOS bodies has a 44 mm flange focal distance. That's a problem as you cannot mount the FD lens inside the EOS body to shorten the distance to 42mm. There has to be room inside the EOS fullframe body for the mirror to move. So, optics are involved, at least for FD to EOS, that perform similar to your question about extenders, at a factor of 1.26x. If the EOS body contains a cropped sensor, then too you have to consider that crop factor, 1.6 for a Canon DSLR.

The Sony E-mount has a flange distance of 18mm and a 1.5× crop factor with APS-C sensor cameras and a 1× crop factor with full frame sensor cameras. The metabones adapter for FD to E is simply a metal donut that holds (adapts) the FD lens to the necessary 42mm distance from the camera sensor allowing focus to infinity as well as close focusing. See topic "Using FD lenses on other mounts" within https://en.wikipedia.org/wiki/Canon_FD_lens_mount.

For the other lens mounts you mentioned, you'd then have to investigate their specific flange distances vs the candidate EOS bodies and the specifics of the candidate adapters, including whether they're empty donuts or include optics (glass) and what magnification factor is involved, if any.

You seem to have multiple topics mixed together. No wonder you can't find a clear explanation.

First, off, the arithmetic of an extender / teleconverter is the facter (say 1.4x) against the focal length of the lens. In your example, that is 1.4 * 50 = 70. Not sure where you ended up with 77. This is hypothetical, as I'm not sure if a 3rd party tool could extend an 50mm lens. Nikon and Canon would not.

Next, you keep saying 'adapter' so we can only assume you mean 'adapter' as in a product that allows a lens of one mount type (say Canon FD) to a camera body that used another mount type (say a Sony E). Everyone of the many many combinations would then need to be investigation for the specifics of the lens and the specifics of the camera / sensor. In the example of a 'full frame' Canon FD lens and a 'full frame' Sony sensor, the angle of view is unchanged by the adapter. But, other adapters many include a crop factor. There's no universal generalization that can be made.

You can use Topaz as a plug in from LR. My preference is to start in LR then to PS and from PS utilize different layers with Topaz or other software. AI Clear is pretty good, you'll need Topaz Studio and purchase the AI Clear and several other effects. Your other option is to just use Topaz Studio (Free with a few capabilities) with some additional purchases, it offers layers and working with RAW. As far as Topaz performing better than LR, yes in several of their effects, Precision Contrast, Precision Detail, HSL Color Tuning, and you can utilize artistic effects such as Impression, Glow, Simplify and Texture Effects. I'm sure you'll find more about Topaz vs LR if you search this site - Good Luck and have some fun.

You could have done this yourself ....

a) dump the EXIF data from a CR2 using EXIFTOOL and pipe the output to a text file, use parameters: -list -EXIF:All -sort
b) with same parameters, dump the EXIF data from a DNG and pipe to second text file
c) import the data to Excel and run a look-up function comparing the two files and identify what is missing in the DNG
d) save the results to a text file and attach to UHH

From an EOS 7DII CR2 file, the attached list of 108 values are removed by Adobe in the DNG. The dump from the CR2 was 381 and from the DNG was 485 so in Excel, the VLOOKUP function was used to identify the CR2 values that do not exist in the DNG values.

I own a D800 and D810, and I do not rely upon "canned" programs or adjustments that they provide - I think they call them "picture controls" - I prefer to tailor and adjust my images to my taste and if I decide to go in a different direction with an image, I can simply create a virtual copy of my raw file without any adjustments and make it the way I want. Once you use a picture control or other built-in image enhancement setting on a jpeg all that data that is not used to create the image is discarded forever - there is no going back.

So, for my photography, I have no use for those "features" you are writing about. Also, the D600/610 is 6 yr old tech. So no, it lacks the innovation the FZ80 has. And what's more, the FZ80 packs 18 mp onto a tiny 1/2.3-inch sensor, compared to the D610's 24 mp on a full size sensor. The individual pixels on the FZ are 1.59µm² compared to the D610's 35.4 µm² - there is no question which one is going to produce better images in low light with high ISO. Comparing the two is like comparing a Bugatti Chiron ($2.5M, 15 mpg to 35 mpg) to a Toyota Prius Prime ($30K, 133 mpg) and panning the Bugatti because it only seats 2 people, has no room for luggage, and doesn't include a JBL based entertainment system with integrated GPS, remote climate control, SafeSense collision avoidance with pedestrian detection, blind spot monitor, backup camera, satellite radio, dynamic radar-based cruise control, lane departure alert with steering assist, and fully automatic headlights, high beams and windshield wipers.

Each car fits a certain set of widely different expectations - same goes for cameras.