You should only do about 12 lifts. Take a break for about a minute and do it again. You should do about three sets with 12 reps each, then move onto your next exercise.
There is no set number. The weights vary as does ankle resistance. I would recommend starting from the lighter end to get feel of how comfortable they are then start adding the weight. Remember it is easy to tear a tendon - so go easy and gauge your resistance.
It depends what weight of ankle weights you are using. If you are using light weights, you should aim for more repetition (15-20 reps). If you are using a heavier weight, you should aim for less repetition (5 reps).
Assuming you do not have any medical issues, you should start with a set of 15 leg lifts or until the muscle feels tired. You can increase the number of sets or the amount of weight as you get stronger.
This completely depends on each individual and their ability. I would start with 3 sets of 10, and then see how you feel. If this is too easy, increase the number of reps.
