Your first argument about Obito knowing, He did not know. Let me tell you why:
1. Because he did not know that FTG marks lasts forever (Unless you become 10 tails jinchuriki, or that object which he put mark on is destroyed).
2. He also did not know that Minato had a FTG v2 in which he can teleport to his kunai and attack his target. Therefore your argument on this is invalid and based on your own ASSUMPTION.
Your point on chakra cloak, you could be right. FTG still counters kamui, it has been demonstrated before successfully. Minato did not take 1 hit in that fight while delivering several large blows to Obito. The reasons are still not clear, i still firmly believe that the user can teleport in and out of kamui land if there is a mark. Let me go do some research on it and get back to you =]
You also mentioned "If this is truly the case, I could mention a ton of reasons too, more than these 4." I truely did not understand what you're saying here though. Just to be clear my statement was "3. I never stated one opinion where you STOP kamui, you don't stop kamui. Everything i presented here is a tactic/technique where you can HURT or KILL the kamui user." Could you clarify on your statement please.