You're trying to chew before you can bite. Don't try to take so much in at one go. You say you have a teacher? Ask him these questions. Ask him to teach you songs with these barre chords, so you can properly make use of them.

Listen to songs, you'll find that every song has a different number of strums per chord. It's whatever suits the rhythm. Different songs also strum a different number of strings for each chord too. There's too many variables that there is no definite answer.

Slow it down a notch but keep at it, you're just trying to take on more things than you need to.
"Air created the greenness. And once you've got something, that leads to otherness." - Karl Pilkington.