I feel embarrassed to ask this, but I haven't used the GECK in like forever since FO3 was just not working after the last couple of patches for it; Where is the menu with the mod's details like author info and stuff? I just need to edit some of that and I will be finished with this mod...

I don't do that through the menu. When you select File->Data... and highlight the mod, you can edit the info on the right.

I am not able to edit it in the GECK for FO3 or NV. It crashes the GECK and corrupts my file. I use FO3 edit to change the name and description.

That is funny becuase I had that problem with Oblivion but not FO3 or NV.