I think upgrade status should reflect current status, not the status after purchase. for now if I see 20/20, I think it's fully upgraded, but it's not, it will be after one more upgrade.
Why rockets can't retarget themselves after their target was destroyed? It's not nice to have all rockets fired at an asteroid, which is blown up by the first of them, and them the main strike force appears.
Yeah, it may be not obvious :) i'll think about it in gui revision later.