NL25 Queens on low board

[Poker monkey]

I think we need to bet at least something for value on this river. There aren't that many draws out - 76 is the only one, (and I'm not sure that calls a PSB on the turn), and that will often give up on the river anyway. His hand looks more like a middle pair to me. The question is, what's the most +EV bet size on the river for me? Also can we ever fold if we bet half-pot on the river and get raised? Does being able to fold the times we're beat add to our EV?