Regarding WoW folders I suggest transferring/backing up the following:
Your WoW install folder is the folder called “World of Warcraft”. Within that you will find subfolders for each type of WoW you have installed. Main one is called “retail”, classic is “classic”. Within each one of these sub-folders I would suggest backing up/copying the following folders:
-“WTF”: the warcraft text files folder, this has all your addon settings, this is where addons save their settings and data and your configurations.
-“Interface”: this is optional, this has your actual addons but no addon data, it might be smart to just reinstall your addons using your client but if you do have any addons you’ve personally changed in any way, well they’re in here.
-“Screenshots”: this is where all your screenshots are by default. Many people may not care but lots of people have many memories in WoW screenshots they may want to save.
I personally suggest starting up the game at least once after installing all your addons, logging into a character, then logging out again then replacing your WTF folder with the one you copied over.