In GIMP go to Edit → Preferences. Then at the bottom open the Folders preferences and select Fonts. You usually will see two folders listed here. You can add the fonts to they user folder listed there, or you can even add a new folder for using the Windows fonts.
After doing that and adding the fonts to the folder, GIMP needs to reload the fonts. You can do that by restarting GIMP.
1.a. i see folders named temporary and swap, which one do i use?
b. i don’t see how to add a new folder
is it better to add the fonts to linux therefore and linux AND gimp both will have them
and the most important question of all - which i can’t seem to find - where do i get the microsoft fonts for a specific version of windows (i’m assuming each windows version used different fonts)
1a. I don’t use Linux myself, so I can’t comment on which one is better to use
1b. Above the list of folders, the left most button allows you to add a folder. Be sure to click OK afterwards.
If you want to use the fonts in other programs on Linux too, then there is probably a better place to add them globally. I am sure there should be online documentation about where to do that.
You probably need to own a copy of Windows, and even if you do, you may need to check the license if you are allowed to copy the fonts.
(I’m using a self compiled version so my “system” folder isn’t standard, the 2nd folder is likely /usr/share/gimp/2.0/fonts for you.
Once you have dropped the fonts in the directory, you can ask Gimp to refresh the list without restarting, using the fonts lists dialog: click on this icon: