1. If you mean the "<bad string>" message... every time I think I've fixed that it shows up again somewhere else. If you click the Type box above it and choose any of the options, I believe it should go away and everything should work fine.
I'll add that to my list of things to look at, but I don't have a ton of time for really deep bug fixes right now.
2. I can only reproduce that error if I click the Set button when there are 0 results available from the current search. I'll add a check for that, but are you getting it in a different circumstance?