ya know StoneRidge it is odd that your above thread did not get any response. I know for fact that most of those subjects and questions have been addressed on these forums before. If I can find some of the links I will post them here for others. I know from further reading your reports that you have long since passed the point of needing this thread answered.
I recall that Overlander 64 had a thread long ago about the refinish of his bathroom/s. He is one of the forums best reporters. However I recall he had his work out-sourced. (He hired it done.)
There have been at least several other detailed reports of DIY bath refinishing.
The ceiling sections are "officialy" known as "domes" and I believe are made of fiberglass. The bath panels and fixtures are made of ABS plastic. Apparently there are dozens of forms (formulas) of ABS plastic. I know there are threads here about "plastic welding" which deal with attempts at fixing the damned stuff.
As for caulking there is a long thread on that subject, but it focuses mainly and perhaps exclusively on exterior caulks & sealers IIRC (if I recall correctly). Interior wise I would think that the dreaded Silicone could be used on non metal applications, but wouldn't the deluxe (improved) tub-&-tile caulk make the most sense? Not sure how many colors it comes in, nor whether it could be colored (then how would you get it back in the tube?

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Again I know you have long since moved on with the AS-rehab but I post here mainly to keep this important thread from being a dead stub.