jwatts---Sounds like you got it all covered there, LOL!!!
ZDTR---Stay away from OSB and go with decent plywood that you can paint to really make it even more resistant to moisture. I already have premade dropdown windows for one I'm going to build next Spring and it will have either shingles or metal over the sloped roof for extra water protection. It's going to be 4'x4' and will be set on concrete blocks in the swamp I hunt in northern Michigan. I have materials left over from an addition I put onto my cabin a few years ago, so about all I need is to either rip some leftover 2x4s or buy a few 2x2s for all the corners. I plan on doing it during turkey season and the deer will have until Fall to get used to it.