So, "while engaged in Melee combat or another chr is trying to block his attack within 2 meters suffers -3 modifier."

1. Does that mean anytime someone took a melee swing during the combat round?
2. Does being ready with a melee attack count?
2.A. Ready within reach +2 meters?
3. Does the melee opponent have to equal or exceed the number of initiative passes?
4. Can someone with a gun move 3 meters away and fire without penalty?

Any other thoughts/suggestions?

I'd say it's best to take the rule litteraly. It applies when the character is engaged in melee combat or someone is trying to block his attack within 2 meters. If you go beyond the dice and actually have a picture in your mind of how the combat is played out, there should be no question about when it applies. There's not even any reason to drop the catch all reply "GM's decission", because it should be entirely obvious to everyone involved if there is only the slightest amount of storytelling involved in the fights in your game.