1. The various video packages are all just different versions of the same movies. They have different scaling and color/darkness qualities, but they are all almost all the same content. Which FMV package did you install in bootleg? I'm interested in the slow codec performance on them and I think my first suggestion would be to change the movie path in bootloader config to the movies folder in Final Fantasy VII/data/movies. Starting with the actual opening movie, those are some of the best examples of these old FMVs in existence. It's one of the few things SE really did to the rerelease at all.
2. The backgrounds? From the FAQ:
➣ I installed FF7 Game Converter from STEP 0, and the FacePalmer field textures don't appear to be working.
Download
Omzy's FF7 Field Textures.
Extract the "field" folder into the ...\mods\Bootleg folder.
Edit "Run FFVII-Bootleg.bat" and remove all /AFFINITY F. Save before closing.
EDIT>Whoops, this is only for XP i guess... made no sense to me either way lol, changed in FAQ
3. Don't really understand this issue, none of the names of the characters have been changed at all? The items? What do you mean it fails on various modes? Are you trying to reinstall bootleg on top of itself with different modes? The retranslation itself is a preview and only goes til so far in the game, the name changes and item changes should be permanent tho, unless you reinstall Menu Overhaul (which can be done multiple times after bootleg without uninstalling it) and uncheck the retranslation completely.
4. Known issue, very irritating I know, should be fixed soon (yay)
5. Out of scope. Test with another pair of earphones or another motherboard