Re:
Well, I don't know anything about Ballistic so can't say much about the fork your running, you'd best seek advice regarding that from someone more knowledgable.
Regarding the Koa, just looking at the height of the seat tells me your probably on the right size and anything smaller may be too small. The 120mm stem your running (which I believe is shorter than what Kona offered for that size frame) and the proper P2 should give you decent, probably fairly quick handling. You could always try a smaller frame but I reckon you may feel a bit cramped. Personally I prefer a smaller frame though, so who knows, maybe it's worth a try.
Well, I don't know anything about Ballistic so can't say much about the fork your running, you'd best seek advice regarding that from someone more knowledgable.
Regarding the Koa, just looking at the height of the seat tells me your probably on the right size and anything smaller may be too small. The 120mm stem your running (which I believe is shorter than what Kona offered for that size frame) and the proper P2 should give you decent, probably fairly quick handling. You could always try a smaller frame but I reckon you may feel a bit cramped. Personally I prefer a smaller frame though, so who knows, maybe it's worth a try.