Coffee will be huge this week, as for a #2 you might be stuck using LJ this week with K. Smith likely out.
As for your trade having both Palmer and McNabb can be nice if they both stay healthy the rest of the year. McNabb has a bye this week and I wouldn't be surprised if they sit him Week 5 as well against Tampa Bay at home. (Kolb has looked good and no reason why you would question putting Kolb in for one more week for a weak Bucs team). I think Grant has some great value, especially with the cold whether games just around the corner. Last year he tore it up the 2nd half of the season.
As far as Brady goes, everyone is expecting him to blow up anytime soon, so who knows. I would take the trade if I was you and maybe even if you have room put Kolb on your bench as your 3rd QB. I just think Grant will be able to secure your RB situation. Good job Handcuffing Coffee though that might save you this week.
Good Luck!