Hitching on the island
Hitching on the island is completely possible. Grab a map of the island and start walking toward where you would like to go. A sign in both English and Melayu (Ride! Tumpang!) would help. Motorcycles are aplenty for tourists and locals alike. Avoid riding without a helmet in the tourist areas because police will try to pull you over (by waving you over while they're standing on the sidewalk), which the driver can and should ignore to avoid a fine of 300 Ringgit (100USD) per person without helmet.
The tourist strip is littered with expensive restaurants. The strip has a few local restuarants for roti and Indian food on both ends of the strip, not much for cheap food in the middle. The walk is short and well worth the food. On certain nights (Friday or Saturday) there is a night market in front of the aquarium with good, cheap food as well.
Accommodation and Sleep
Sleeping outside and on the beaches will not get you too much attention or any trouble. Making friends on the beach should get you a place to crash for a night.