The fortress is open from 09:00am. If they decide to visit all sites on top of Tsarevets hill including the Patriarch church and the remains of the former Palace, the minimum duration will be 1.30 min. They need min 30 min for walking along the Samovodska craft street, so total duration of the visit is 2.00 hrs as I described in the SCF. So, lunch at Pravets remains for 13.00. Arrival in Sofia at 15.00. Yes, shops will be still open.