Re: recaulking tub
The joint needs to be thoroughly dry before recaulking with anything, or your efforts will be all for not. You can wipe the joint down with a bleach solution prior to caulking to kill mildew that would otherwise be trapped by the caulk.
IMHO, it is wisest to use a tub and tile latex caulk because the caulking will fail eventually and latex can be removed. Silicone leaves a "greasy" film that no other caulking, including silicone will stick to, and it's also much harder to work with than latex.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!