leaves a cutting stone at Q15. If you are sure you can handle the fight, then it might be OK to invite W to run with this stone. But why not simply capture at P14 (geta)? The resulting B thickness is superior to the small W corner territory, and there is no aji left for W to exploit.
might be playable, but it is risky. The previous W extension was not an obvious overplay. The W position may be a bit thin, but there is no need for an immediate invasion. If W later has to add an inefficient stone around D12, that would be good enough for B.
First thought is simply connect at Q5. After that, P9 would make territory while attacking. (If the territory below P9 looks too narrow, that might be an indication that 
was the wrong direction.) 
Can this be P9? (Please verify that W cannot cut.) B would like to get out as fast as possible, to split the W positions here, creating two weak groups. 
and 
are big moves, but the right side fight is still urgent. Play around O9 by B would initiate a severe double attack, while a W move there would force B to live small underneath.:b127: was a blunder(?), but consider continuing with O8 anyway. After that, B can capture the entire upper W group cleanly with one more move, while the B stones below are not all completely dead. This looks like a good trade for B, especially considering the alternative.
