Great team! Trade for pitching! (Or, I assume, you are in a league with few players.)
1. I would recommend Matsui, who seems to offer good AVG and power.
2. Luis Gonzalez is also hard to ignore, but I suspect given the Arizona lineup vs. the Yankees, that Matsui will have stronger numbers.
3. Damon gives SB, but doesn't Ichiro plus Soriano put you in good stead already? Damon only if you want SB.
4. Ellis is unproven. I say this as an A's fan. He won't bat .387 for the season. (I personally suspect, he'll end up a number 9 hitter, once Singleton catches fire.)
5. I have no opinion on Milton Bradley.