I wouldn't do it. Schaub will have his receiving core all back and this should help. I'm not saying he'll be great, but better. AP is solid
I don't think Brees can get great games without Bush and Thomas - a lack of running game is killing the long ball and everybody seems to have caught on. McCoy has been great, but I feel he has the best chance of this bunch to miss games due to injury.
That's tough. I think you should keep your guys. AP is going to keep lighting it up and Schaub is going to get a healthier Andre Johnson and Owen Daniels. If you did do the trade, I don't think it would be catastrophic, unless a couple of points decides whether you accomplish your purpose or not.