...teams defenders, if so, is this a strategy used in the game?

No, sometimes it is a foul along witha yellow card or sometimes a red card. If this happens in the penalty box, its a yellow plus a penalty kick.

Block team defender its depend how you block. If serious tackle maybe can cause foul and card as well. Normally yellow. But if not so serious your ooponent only rewarded freekick.

Most of times it is only punished with a freekick ! But there are lots of times when the referee doesn't see what you are doing, and the match continues and you will get unpunished !