Answers are yes, no, and yes. 1)The fresh water tank had some moisture due to condensation so there could be some nasty stuff growing. Put about a cup of bleach with half tank of water in the tank (ratio isn't critical). Let it sit overnite, then drain the tank, rinse 1 or 2 times, then refill. I use bottled water for at least first time out for drinking, until there is ZERO smell of bleach coming from faucet. The other thing I've done after bleaching the tank is to leave it in while driving first day, then use a full hookup site, open the greay water tank and open the faucets flushing system out 2) No need to do anything with these tanks, 3) OK to leave wastewater tanks as is until you use coach.
Enjoy the lifestyle see you down the road
2010 Journey, 2015 Equinox