Painting - caulking around the window frames

I'm building a shed, twelve feet by twelve feet by twelve feet. It will have a pitched roof. What distance should I put between the studs and what pitch would you recommend for the roof (heavy rain, little or no snow)?

Feel kind of silly asking this, but can please some tell how to properly caulk around the window frames. I applied first coat of paint prior to installing new windows, now I want to make sure there is no place for spiders to go to. Should I mask the frame before caulking, then let caulk to dry and paint using the same masking or should I mask only before painting? Don?t want to ruin brand new windows, I , of course, done my share of ruining things before?..

thanks,

If you have the time,then mask up the windows an 1/8 of an inch onto the glass,and then caulk all around,smoothing the caulk with your finger..Then apply your undercoat& gloss,wait till dry and take off tape. You wont see many pro`s doing this as they like to think that they can "cut in" as accurately and much faster...Im one of them,but take no notice of us...You go ahead..