Quote:#1: I´d give 5. ...Bg4 a ?!, because the later trade of the light bishops favours white - FALSE or TRUE?!
You are right, but for the wrong reasons.
5...Bg4 is too early because White has not committed to Be2. This means that White can play 6.Be3 0-0 7.Qd2! since after 7...Bf3 8.gf3 Nc6 9.d5 Ne5 10.Be2 White has a definite advantage. If Black prefers 7...Nfd7 by analogy to 6.Be2 Bg4 7.0-0 Nbd7, then 8.Ng1! Nb6 9.f3 Bd7 10.Bd3 is very good for White.
Also, 7...Nbd7 is imprecise because Black cannot put pressure on the d4-pawn. Better is 7...Nfd7 to prepare ...c5 or ...Nc6. Your reply 8.Ng1 lets Black off too easily because after 10...e5 it's a normal Samisch where White has exchanged his bad bishop but Black has an extra tempo compared to usual proceedings. Instead I'd follow Kasparov's example with 8.h3! Bf3 9.Bf3 e5 10.d5 with a pleasant advantage for White. Black can't even play for a kingside attack with ...f5-f4 because he lacks the key light-squared bishop.
Quote:After 10.f3, white plays a maroczy-structure, without the light bishop this structure is even better?! - F o T?
This isn't a Maroczy Bind structure at all. This is a Samisch pawn structure. White has a small edge after 10.f3, but you could have had a larger advantage with 8.h3 earlier.
Quote:#3: 12.Rb1 - After 25 minutes of thought, I finally played this move. An engine doesn´t help in this position, what would you play and why?
12.Rb1 doesn't improve your position much because often White can play b4 without the preparatory move Rb1. Instead 12.d5! is screaming out to be played. You secure a permanent central space advantage and prepare queenside play with b4 and c5. If Black plays ...c5 and ...f5-f4, you are clearly better because you can gain the advantage on the queenside with a3/b4, whereas Black can't do anything dangerous on the kingside without his light-squared bishop. If you're wondering why Black's light-squared bishop is so important, have a look at Gelfand-Kantsler, Israel 2001. Perhaps Black should play 12...Qa5, but then 13.a3 or 13.Rb1 preparing b4 is quite strong. Black has no counterplay and will probably suffer for the rest of the game.
Quote:#4: 14.c5 - what would you play and why?
Seth_Xoma is right. 14.c5? brings Black's position completely to life because White is not adequately prepared for such an advance. Again you should play 14.d5!, this time with a clear advantage because Black has fiddled around with 12...Kh8?!.
Quote:#5: After 15.Bf2 white has a strategical winning structure, do you agree?
No. After 15...ed4 16.Nd4 Qf6 17.cd6 Nd6 White has a minority attack on the queenside with b5 and a passed pawn on e4, but the e5-outpost for the knight partly compensates for that.
To be brutally honest, this game makes me doubt whether you should have the Classical KID in your White repertoire. I think the Fianchetto Variation would be a more suitable choice for you.