![:lol:](./images/smilies/lol.gif)
lordy, lordy, I go away for a day and you folks go post-crazy on me!!!
Okay:
Reparo charm: could be, she makes a point of showing it can fix things, but not make things exactly new...
Mirror at Grimmauld: don't think so... If it had been me, I would have kept with me any POSSIBLE (even if it's unprobable) tool to reach Harry before he got too deep into the Ministry of Magic... so I would have been calling "HARRY POTTER!!!" into that mirror, praying that he would pick up.
Mirror being used again: most likely... haven't a clue how, though?
Kreacher using it: once again, don't think so... if elves aren't allowed to use wands, I don't get the feeling they'd be allowed to use a lot of random mysterious magical objects.... but that's just my feeling, no proof to back it up... however, I don't think Kreacher would use it to reach Harry, because... well, I just don't. I don't think it fits in with Kreacher. I would see Dobby (if he were in a position to have the opportunity and need for it) using it to reach Harry, but not Kreacher.