Please quantify "huge". I work with a 3000 page PDF constantly. I made a million page PDF once, and found it tedious to work with.
If you have the catalogs as PDFs, don't involve InDesign in combining them, unless you need cross links.
Huge = about 40,000+ pages.
They are currently in 4 separate catalogs. I'd like to create an "all-in-one" catalog that would act as the "cover" and the table of contents for the entire compilation. I hope that makes sense? As I stated, I am quite familiar with InDesign, but have only done very minor tasks in regard to Interactive PDFs. I'm just trying to figure out the best, most efficient way to make this happen.