For Analysis

Trading Bishops for Knights is rarely a good way to start a game unless it's a Ruy Lopez or there is a plan involved.

Creating a fiancheto without the Bishop weakens the pawn complex.  It's worse if the opponent has the queen and bishop to penetrate the weak squares for a mate.

Move 13 brings up the TRIP method of defense to mind.

When confronted by an attack, such as a bishop vs rook one should:

Take the attacker

Run from him

Interpose a pawn or piece

Protect the square that is attacked.

The calculations should be made in that order.

Black needed to move the rook and that's it.  Going off on a separate attack rarely yields enough compensation.

Having a material advantage, the plan should switch to restraining the opponent and simplification such as Qb4!  You never want Queens on the board if you are uncastled because it leaves room for quick mates or perpetual checks.

I thought sacking the knight had an idea such as chasing White's knight and skewering the queen and king.

Trading rooks was an excellent way of ending the resistance but the follow up move seemed unexpected.  Always be on your toes when leading in material because your opponent may still be looking to get it back or escape with a draw.

Take a look a 49.Ke2.  Pattern recognition is on of the cornerstones of chess.  Bobby Fischer once checkmated (Yes, checkmated) a grandmaster in the middle of the board with a similar position except that Bobby didn't leave him any exit squares.  Black had better chance with a queen check instead of a knight check in this position.

Notice how the defending queen is mopping up the pawns.  This is why you must always exchange them after achieving a material advantage with an uncastled king...