For ex. if i am level 100 and above and i kill a monster will it still drop level 55 gear/items?

good luck killing stuff at level 100, you'll find 70ish is as far as you'll want to go, so generally level up till you can mq then hit it and redo it.

But yes anything past level 55 (lower if down td's/fighting ep's) can drop 55 items

ok thanks