The ProAnimator is what you would need to get. The Invigorator plug-in for After Effects won't work in Combustion. ProAnimator contains all the features of ProModeler so you won't need that too, just ProAnimator.
ProAnimator will let you create beautiful 3D text and logo animations very quickly and very easily. Most people who use it don't have any previous 3D experience. The ProAnimator will render movies or frame sequences which are then used in C4 just like any other movie file. The alpha channel is built into the movie so you get perfect composites with no matte lines or black halos.
I just got back from the Broadcast Design Association conference and I can't tell you how many happy people we had coming up to the booth and telling us how happy they have been with the program.