How old is your DD2? I personally wouldn't let her go longer than 3hrs during the day because it will help you establish your supply and assist in differentiating day and night for her. Also in the first few weeks babies can be quite sleepy and not ready to demand so can need to be woken.

One side or both I would leave up to the baby. Start on one and when that has drained offer the other, whether she takes it or not is up to her.

How do you feel she is going? How are nappies? Weight gain?