In descriptive the knight can be N or Kt but the lone K is King .
help with opening

Captures in the opening often helps the side that recaptures.
Compare two of black's moves to two of white's:
Black: Bg4, Bxf3
White: Nf3 Qxf3
Black has spent two moves with the bishop, and his position has nothing to show for it (he traded it off). White spent one move on the knight, and one move recapturing. The result is the queen was brought off the back rank. So black has lost a little time.
Does that mean you're winning? No way. Just keep developing quickly and castle. The result will be your position is a little better than it could have been, and likely quite comfortable.

h3 in the opening is usually a move made by beginners. When its vital to control g4 it's good. Otherwise it's actually bad for the same reason capturing a lot in the opening is bad, it makes your development slower.
Development is getting all your knights and bishops off the back rank, castling to a side where the 3 furthest flank pawns have not moved, and then moving your queen off the back rank so now the rooks have no pieces between them.
http://www.chess.com/article/view/the-principles-of-the-opening

You should be aware that a Bishop is slightly stronger than a Knight. If he takes your Knight on f3, take back with the Queen and you are fine if not sligthly better.
See the diagram...

by the way in descriptive notation the knight is called 'N'. K is king.
Aren't we dealing with algebraic notation?

A lot of people have this knight pinning obsession, and it's usually not so bad. Sometimes those pins can really kill you, but, for the most part, you get the two bishops for free - which is a real advantage even at lower levels. One thing you ought to start thinking about though is the concept of the CENTER - I assume you know to put a pawn in the center when you begin the game (probably e4 - the king's pawn), but did you know that *two pawns* - the classical center - is the ideal? What's more, the queen defends her pawn, so you can often play d4 (the queen's pawn) to very strong effect in king pawn structures. I don't want to confuse you too much, but there is an old saying "If your opponent attacks on the flank, you strike in the center. Try thinking about that idea and experimenting with ways to hit the center and get the bishop pair. You'll be (pleasantly) surprised when you see your *opponent* shaking his head at the bad position he's earned himself.
I play a gentleman at work each day and he continually moves the same way.... when I move Kf3 he will immedatly move Bg4 ... then he will immediatly take the knight on the next move .... He says I am too dangerous with them .... sort of messes up an opening like ruy lopez, Kngs Gambet, I am fairly new to chess....just wondering the best approach to this problem .... BTW he is hard for me to play as he plays this wierd mixed up way ... you can never decide what to do as he plays this conveluted chess strategy that is his own making .....