Yeah I've added kettle bells and they really make a difference. As above start with lower weight heigh rep. I'm feeling muscle soreness after yesterday's workout and missing workouts last week.
Depends on your size/strength. Just pick a weight and do some trial/error. There are multiple ways to get effective results if you don't have access to a variety of weights, higher reps/sets, more weight, or performing the movement slower to increase the total time under load.