Toilets, Sinks, Showers, Tubs and Disposals - Replacing Old Mouldy Shower Stall Door

This is a fiberglass shower stall. I've got the door and all hardware off. Using a razor blade scraper and putty knife I've gotten all the old caulking off too. I want to super clean the stall opening. Rubbing alcohol seems to be working. Is acetone a no-no on fiberglass? I'm trying to get the area as clean as possible before installing the new door. What's the best damn near totally mold resistant sealer to use on the new install? How hard it it to get the door properly adjusted after installing the thing. Stall seems pretty square and is not damaged to any great degree. Does it matter what side the door opens? The shower sprays from the right, I want the door to open from the left. The old door opened on the right and was a real PITA since you had to walk around the door to get to the sink. The regular bathroom door also would also interfere with the shower door. How does one get a nice even bead with the caulking? Wet finger? Special tool? I also replaced the sink today and need to seal the seam to the vanity top and want that to look good after I'm done.
Any advise is greatly appreciated. I don't want to do this again.