Have you checked this?
The BIG List of Mods
Yes, but it's beyond overwhelming. That's why I thought I'd ask.
Has Grimmy actually done a complete Battlescene retexture? In that thread all I can see are "World Map" retextures. And Felix Leonhart appears to have only done 11 of the 89 Battle Scenes.
So to answer my own questions:
Q) I was wondering if someone could explain to me how I might go about increasing the texture resolution of the Battle Scenes and World Map?
A) ASK SOMEWHERE ELSE!
Q) Some games are great at allowing you to multiply the texture resolution by four (for example), add a lot more detail, and then slot them back into the game. Is FF7 friendly to that?
A) ASK SOMEWHERE ELSE!
Q) Or has someone already made a decent high-res texture pack?
A) World Map: Grimmy has done one. Felix Lionhart has done one (arguably better).
Battles Scenes: Felix Lionhart retextured 11 of the 89 scenes. Unknown if anyone else has ever managed to do all 89.