The engineers do fuel drain checks each night as part of their daily checks.
Jepps are amended by an outside contractor (sometimes Jeppesen themselves) or by the airline ops department, in larger airlines there are two sets for each aircraft (one in the aircraft one being amended) these get swapped out at each amendment cycle. In the UK I have seen amendments for one or two airports on the route network given out to the crew to put in the books, this was in addition to the amendment service.