I think there's about a 1 in 3 chance Felix outscores McFadden this year. There's also a decent chance this is the last time to sell Colston for value. I think it is an ok deal for you, especially on a loaded team.
God help me, but I would take Baldwin off that list. I hate him but if you're going to hold someone with that roster you have to go for ceiling.
Given how many people are unowned I wouldn't feel great pressure to grab someone. Preserve your waiver priority/dollars for someone who delivers W1. If you do add someone, you might look to short term prospects like Armstrong, Hagan, Devin Hester, Jordan Norwood and then try to flip them for a 2012 pick if they look startable. I think this is better than marking a guy like Baldwin just to drop him 2 weeks from now after he starts slow. Because you know he's going to start slow.