Kawasaki should be the starting 2B against RHP IMO, batting 9th.
I never in a million years thought I'd say this about ANYONE, but I'd rather move Bonifacio over Davis (who has, admittedly, grown on me now that he's being used more effectively.)
I don't think it would take that long for Kawasaki to adapt to 2B, the position is very similar, and it's not like he's just going to forget which bag to throw to or something.
You're 100% correct that Kawasaki will be back in a few weeks.
DeRosa is a right handed bat off the bench with some pop and (limited) positional flexibility. Bonifacio, Izturis and Kawasaki are all very similar players and the move should come from one of those 3 (and it did.)
Yeah, Melky needs some time off, he's brutal in the field, and he's scuffling badly at the plate. Hopefully it's not 100 games (unless that lets AA out of his contract, wouldn't shock me of AA had a "get caught with PEDs again and the contract is void" clause in there...)