The number I do and the number you do are sure to be different. You could start with three sets of 10 reps and see how you feel - just always give yourself time at the top to fully release the pelvic floor so that means slowing the movement down to allow for long engagement followed by long release. 3x10 will probably wear your floor out if you do them a bit slower. I wouldn't worry about reps, just add weight to make them more difficult.

As for weights, I said to ADD weight, not GAIN it :). Gain weight if you want, but hopefully it's muscles and not Honey Buns! For me I hold a 30-50lb kettlebell while I do squats.