When playing the game at my native 1920 X 1080, the view is the right size, but my health and air metres are tiny so it's impossible to accurately judge Lara's health and oxygen. The only way I know to sort it is to set the resolution to something lower that takes up most of the screen, but displays the bars longer and larger.

I shouldn't have to do this and it's annoying. Is there a widescreen patch to fix that issue? Also the FMVs have window borders which is also rather immersion breaking. A link to the patch for those will help too.

Install Peixoto's patch, then download the remastered FMVs and put them into the FMV subdirectory of your TR2 installation.
This should fix the cutscenes and enhance the game's widescreen experience, but I am not sure about the health bar because it is hardcoded.

It didn't work. Removing the old RPL files just skips the FMV sequences entirely and leaving them with the new bik files in there too does nothing.

Renaming the new files to RPL doesn't work either. What do I do?

As for the patcher, Norton blocks all of the main files like the Help.exe, Injector, Launcher, pexioto.dll, compiler etc and says they're a Trojan.

You must add the remastered videos in the folder without removing the RPL files, but you have to patch the game in order to make them work.

I am sorry you found infected files in the patch I suggested: as far as I know many users use it, but I have never tried it myself. After your warning, I made a research about the patch: the author states that some antivirus don't like Autohotkey, which is the program he used to create the patch, meaning that the virus detection is a false positive.
I also tried to scan the file using an online tool and I can confirm some antivirus show the files as infected, while others don't.
Anyway I can't obviously guarantee about the patch's safety, so you may choose to believe the author and install it nevertheless or not: use it at your risk!

Most of the flagging was via download insight and the threat was "WS.Reputation.1" as few Norton users have used it. The risk is medium for those ones i.e.: Compiler, Splitter, injector, Gamma.exe and perixoto.DLL.

Launcher.exe was marked as high risk and was marked with "Trojan.Gen.8!cloud", whatever that is. (Assuming the launcher is even an actual Trojan but don't quote me on that, just in case)

The scan results gave nothing for all of the above except the launcher, which is removed all the time, before I can scan it, for the same reason as above. So because of that I cannot trust the launcher at least, but the others might be safe.

I scanned everything again using Malwarebytes as well to be extra safe, and there wasn't anything dangerous in those.

AutoHotKey.dll was safe when I scanned it too. I don't know if Malwarebytes thinks differently about the Launcher because I don't have the premium version.

What do you think, based on that information?