It appears that Epson does have it in stock on their own website. All of their other photo scanners are showing out of stock there. Due to the pandemic, many people who are stuck at home are tackling the scanning of their photo collections, so photo scanners have been in short supply for almost the last year.

I'm assuming you are using the background removal tool in Photoshop 2020 or 2021. When you use the tool it simply creates a layer mask to hide the background. If you want to use the transform tools on that masked layer you must convert it to a smart object first. I find it easier to bring in the background layer, use free transform on it, and move it behind the layer that I removed the background from.

Check out pixl-latr at pixl-latr.com. They make negative holders for up to 4"x5" film and have a lot of great tips on their website and FB page on how to procede.

You will get much better results using a photo scanner like the Epson Perfection V series. For example the scanner in my Epson Artesian Multifunction is only capable of 24 bit color. My Epson V550 is capable of 48 bits, and the software allows me to do color correction using both levels and curves. For a better scanning performance I use Silverfast software, which allows me to scan to DNG. Silverfast to my knowledge, does not support any Multifunction units.

Adobe applications (Lightroom, Camera Raw, Photoshop & Photoshop Elements) can convert it to a DNG file. However, the basis is still a 8 bit jpeg, probably with an SRGB color space, so the editing information is still limited.

Set the camera to auto white balance. Shoot raw, and use the RGB tone curves to color correct in post processing.

Go to Tether Tools at https://tethertools.com/. They will have the proper cable and additional accessories to assist you in your tethering venture. I do suggest getting their Jerk Stoppers for both your camera and computer to protect the ports.

Check to see if you have Auto Stacking turned on. It's under Photo-Stacking-Auto Stack by Capture Time. If this is turned on LrC will stack your jpeg under your raw. You should see a small box with a number over the photo on top in grid view. Clicking on the box will display all photos in the stack. Otherwise, the settings you displayed in your post are correct for LrC to treat jpeg's and raw's as separate photos.

Some thoughts, you say you do “all” of your editing in Photoshop, but are you working with raw files? If so Lightroom is handling the conversion of the RAW file from raw to tiff/psd. It is also creating the file name for the new file from Photoshop and preserving a database link between that file and the original raw. Bridge on the other hand will simply open the file in camera raw, for movement onto PS. You need to save the file when you are finished (tiff/psd) recommended, Bridge will detect the file however there is no association between it and the raw file that it came from. Also, in my own work flow I find it easier to apply global adjustments (lens corrections, white balance, exposure) in Lightroom/Camera Raw rather than in PS.
If you are dealing with SOC Jpegs you probably want Lightroom over Bridge, simply because Lightroom forces a non-destructive workflow, by creating a new tiff/psd file from your Jpeg when sending it to PS. With Bridge, your original JPEG opens in PS and if you hit save, you have lost your original unedited file.
Do you post files in multiple resolutions or to multiple platforms? Having Lightroom Classic as part of my workflow allows me to do a complete edit in PS at full resolution. I can also leave the file un-flattened, and still publish jpeg copies of it. I can keep multiple versions e-mail, Facebook, print etc, in the Lightroom Catalog without having to store and track separate jpeg files on disk. To accomplish these tasks in Bridge, you need to open PS and complete the task from there.
One thing Bridge does that no version of Lightroom does is track and create PDF files, so I still use Bridge extensively in my workflow, as I often I create PDF’s from digital photos. I do keep my Lightroom set to save to XMP files, so Bridge can see the Lightroom edits.

Photoshop 5 was my first version of Photoshop, prior to upgrading to Photoshop LE 5.5 (the precursor to Photoshop Elements), when I purchased my first digital camera. I have since progressed through several versions of PSE, adding Lightroom 5 to the mix and finally the Creative Cloud Photography Plan.
PS 5 was designed at a different time when, the workflow was scan to pre-press. Although PS CC 2021 has many of the original tools that were found in PS-5 it is based on a totally different workflow, with most originals coming from either digital cameras, or files on disk.
‘You didn’t mention what your editing needs are, but PS-5 does not have capability to convert raw files, which all of the newer versions have via Camera Raw. The selection tools have improved enormously in both PSE and PS-CC. Rather than spending a ton of time trying to make your old software work on your new Windows 10 PC, you would probably be better off with an upgrade. PSE 2021 or the Creative Cloud Photography Plan would both be good choices for you. If you do not want to spend money, I would suggest you download GIMP, and use that. Many people use it and find it almost as powerful as PS CC

Again Epson V600 or V850 depending on your budget or needs. Since it appears you are using Mac OS X Catalina, you will need to use either Silverfast or Viewscan to operate your Epson scanner. The V850 ships with Silverfast, and Epson has it available as a free download for the V550 and V600. Epson scan is a 32 bit application, and incompatible with the new Mac OS'es.

The only problem with your 4490 is Epson won't write new software to use it with 64 bit OS's like Mac Catalina or Big Sur. Skip the V370 and invest in new scanning software, either Silverfast or Viewscan to better drive your current scanner. Note if you are using Windows 10 you will see better results with the new software over Epson Scan.

I'm replying here because I think that it's an important point about B&W workflow. When you set a Monochrome picture style (picture control, etc.) in your camera, it controls how the camera processes the raw data to create the JPEG or JPEG thumbnail, imbedded in the Raw file. The camera also imbeds the information about the picture style into the metadata portion of the raw file. Each camera manufacture handles this data differently, so third party raw converters for the most part ignore this information, and process raw files with their default color profile. If you use the camera manufacturers raw converter to process the raw file, you have the picture controls set by the camera as a starting point. In the case of your Canon Rebel, Canon's Digital Photo Professional Software, will give you the processing starting point, that was set by your camera. You can also set Lightroom/ACR to use camera matching profiles when you import/open an image.

I shoot B&W in Raw. However, I use the monochrome picture style settings in my camera, as well as applying the included color filters. Since third party RAW converters disregard the camera maker's proprietary EXIF, I use DPP4 from Canon to process my B&W images into 16 bit tiff files for final processing in Photoshop.

I think you missed my point. Google want's everyone to use two factor identification for all of Google, including Gmail, YouTube etc. Programs like PSE and Outlook are incapable of providing 2 factor id, so they need to create an application password in Google settings to allow them to access Gmail. It is the same way the iPhone mail app accesses Gmail, and yes Google is constantly reminding me to use their Gmail app on my phone.

My point was it's ok to go to your Google settings and set-up an application specific password, for PSE to access your mail post-office to send photos.