Personally, I'd hang on to Bradley with the roster you have. I think he'll have a decent season, and might be able to help you out down the road (perhaps as a throw-in for a trade or if one of your starting OFs gets hurt).
Obviously, you need a catcher, and I'd consider getting rid of Crawford. With Guerrero, Ordonez and Pierre, do you plan to use him much? Think about packaging him up with someone else and upgrading one of your positions and then pick up a catcher. Or, trade him straight up for a catcher.
As for the catcher situation, if you plan to pick up one of the catchers you listed, I'd go with Phillips in a single season league and maybe consider taking a flier with Mauer in a keeper. If you trade for a catcher, I'd definitely consider picking up Phillips as a back-up. Since he'll play almost every day, you can use him to fill in your starters off-days without sacrificing your stats.
I know you didn't ask, but here are a few other thoughts on your roster. For what it's worth, I think Burnitz is a little unnecessary on that roster. The only exception would be if you plan to platoon him with Pierre when the Rockies are playing at home. Also, you ought to be able to put Burnett on the DL once the season starts.
Hope this helps!