1. The new Tarptent Scarp has a fly which reaches the ground, plus it has a solid inner tent anyway. It's also designed to handle significant wind with the optional extra poles.
The Tarptent Moment should do for 3 season use though, unless you're in fairly extreme winds?
2. Hard to tell. You might need 4-8 liters per day, depending on the conditions, hiking difficulty, and your physiology.
3. Wash with some vinegar to get rid of smell. Darker colors get rid of the stains. :) A non-chlorine bleach might work on white.