Khanpur town is small enough to walk around in under an hour. The railway station, the main bazaar, and the bus stand are all within a kilometre of each other. Auto-rickshaws and motorcycle rickshaws operate from the station for short hops within town, and are cheap.
For the desert sites and Bhong Mosque, you need a vehicle. Local taxis and the few car-rental operators in town can be arranged through your hotel. For the deeper Cholistan trips a 4WD is essential — most are hired with a driver, who in practice doubles as the local guide. Plan a full day for any of the further forts.