Quick addendum for the list. I got the Citron done this week and wanted to point out that the 5000 block is apparently not 5000 damage blocked but 5000 hits blocked which can take a while. I had the tracker on to watch this as I had everything else done and noticed that it would only tick up one point at a time.
I found two ways to get this done in a reasonable hurry:
-Have friends shoot your shield with rapid fire weapons.
-Go to town center as Citron and go down the road a ways to where that All-Star always spawns and use him to get it done. (The nearby solider on the way is less dependable for this I found).
In both cases, when the shield is about to break or does break, pull away and let it regen before doing it again, repeat as needed. I had about 900 of the 5000 from playing PvP matches and got the rest against that all-star.