1. Most people aerate before pitching, although sometimes with high gravity beers you can aerate before pitching, then again a couple times after pitching.
2. My rule is if the tap water tastes good then use it. I've never used bottled water, and I probably never will.
Primary: Apfelwein, Irish Stout
Bottle conditioning: Centennial IPA
Drinking: Super Shpadoinkle Blonde Ale