I am 77 and still going to Yellowstone for 3 weeks in the fall (when school is in session--otherwise it is too crowded) I carry (for reasonably short distances) a 600mm f/4 lens on a tripod. If you want a slightly longer lens, look at the Canon 400 f/5.6 or the 100--400 version II. (The latter is considerably heavier than the former, but both are very sharp.)
You're still a relatively young man. Don't waste your remaining years not taking advantage of your hobbies.
I recommend the 180 macro lens for Canon. Second choice would be the Sigma 150mm. If you are photographing insects with the longer lenses, my experience is that I don't frighten as many before I get the image as I do with the 105mm lens.
Put a strap on your camera and carry it over your shoulder.
I have my images stored on 2 drives in computer and 1 drive off site.
I use a Wimberley gimbal with my 600mm. I highly recommend it. Once everything is balanced, the lens will remain in whatever position you have it in until you move it. (Can move it with the push of a finger.)
I walk with my 600 f/4 lens on a tripod over my shoulder. If I'm going very far, I switch shoulders periodically.
I photograph landscape and wildlife. I always use my long lenses (400--600) on a gimbal head. One of the major advantages of the gimbal is that you don't have to "maneuver around the legs". A descent gimbal allows completely free movement, up and down, left and right. I use the Wimberley, but there are many others available.
Your web site "bald" I assumed would be bald eagles--not bald old men.
I see them every year Yellowstone. Very cute!
Pretty sure I wouldn't want to put subjects in the fridge. Seems cruel.
Switch the camera to back-button focus.
If you plan to photograph insects, I suggest looking at the longer focal lengths. It is frustrating to just get focused on an insect and have it fly away because you are too close. When I shot Nikon I had the 200mm macro lens and it is outstanding. The Sigma 150 macro is also very good.
I don't think you can control depth of field with a phone, so I would not find it useful.
To save money in the long run, I suggest that you imagine the heaviest lens you might ever own, and buy a tripod to support it. Otherwise, you might end up spending a good bit of money on several smaller tripods. I have a Gitzo and an Induro. The Induro (one of the sturdier models) was about half the cost of the Gitzo, but it is sturdy enough that I would not hesitate to use it with my 600mm f/4 lens. I highly recommend you at least check out the Induro pods.
I shoot raw because I don't want somebody in Japan or Korea deciding what a scene they have never seen should look like. Since I saw the scene, I know how I pictured the result.