14.Bd4 looks good here. If 14...Nxd4 15.cxd4 and White has a terrific bind on the position. To break out of the position, Black will have to prepare ...f6.

(?) The product of the difficulties that have suddenly appeared in White's game, one imagines. At the moment he can't contemplate 15.Nd2 Qxc3, and 15.Bd4 is no good either. Maybe 15.Bf4 Qf6 - forced - 16.Re1 or 16.Nd2 are reasonable tries.

Protecting the c-pawn so he can move the Knight. But It looks as though White is thinking of redeploying the Bishop to b2 to challenge along the long diagonal, or is maybe concerned about shutting the rook off from the Q-side. But there's more to be said for 18.Bf4, attacking the Q and putting some pressure down the e-file. Black can respond with 18...e5, whence White has to decide what his prospects are of exploiting the "double half-pin" (the e5 pawn is half-pinned by the B against the Q; and half-pinned by the R against the K - a half-pin describing the kind of pin in which the pinned piece may still move without uncovering the protected piece).

White's 19.g3 really doesn't seem very purposive... Maybe he was concerned about the possibility of ...Nh4, which is safely met by Qg4.

Good point. The N is very well established on f5. Driving the knight away will cost White a deal of trouble on account of a very seriously weakened K-side.