I have heard of putting gumtex in the mmf to make it easier for making bows and such but can you add gumpaste mix? The wilton premix! If so how much?

Yes, you can mix the fondant and gumpaste (premade, but not the powder) together. You can mix it in what ever portions you want. Some do it 50/50 others may do more fondant less gumpaste. More fondant gives you more working time before it dries, more gumpastes makes it dry faster.

I also add a little glucose, it makes it much more stretchier and forgiving.