For the USM and Team Gizka fixes, you don't have to worry: the USM mod also includes bug fixes. Just install the Team gizka fixes and then the USM on top of it. When asked to replace existing Team Gizka files, just say yes (make sure you install the files dierectly in the override folder or it won't work).
As for the Paragorn D20 mod, I've never tried it but I imagine it contains .2da files. If the mod uses the same .2da files as the USM mod, you will have to merge them. I don't remember what Sikon's mod does exactly. Is it the mod that spawns a Master Vash alive? Could you post a link please? I don't know what kind of files the mod includes apart dialogues and scripts.