Try visiting these link: http://www.wfca.org/Pages/flooring-comparison.aspx. They got a chart comparing floor types and cost. You might find these informative.
In painting OSB choose the best primer first. Choose paint that are oil-based. Don't use water-based paints because they'll peel off over the time and make the OSB look unattractive.
Its a new roof so its best to install plywood or oriented-strand board OSB and try coating the roof with an elastomeric coating. These has great insulating properties perfect for cooling in hot weather.
I think you made a good decision on choosing turbines. Here is a good example of how this can be usefulo. Here's the link: http://i45.tinypic.com/1cdvq.jpg
My roof was covered with a heavy snow last winter. I was really a mess. What I did was to have it done by a roof contractor. Luckily, they fixed it before the next snowfall came.