Tactics from my live games :5

here is the game. I loose on time, but many tactics involved in the game

How should white get away from check? 

r1b1kbnr/pp3ppp/4p3/3pP3/1q1P4/1P6/P4PPP/RN1QKBNR w KQkq - 0 9 

Why is the text move in the game wrong?

After ....QxQ what should white do here?

r3k1nr/1p3ppp/pq2p3/1b1pP3/1b6/1P2QN2/P2NBPPP/R4RK1 b kq - 0 15  

white threatens the b4 bishop with a3, attacking it. What should black do here? r3k2r/1p3ppp/2n1p3/1p1pP3/1b6/1P2PN2/P2N2PP/R2R2K1 w kq - 0 19