Regional bus station is located about 7 km from city's centre. You will need to take taxi, bus or private car to get you in. However, we arrived from Kuching early in the morning and we took private car to drive us to nearest guesthouses/Inns for 7 RM. It was fun. We were not really awaken yet when we got offered a can of beer by our driver. It was 6 am. When we were leaving Bintulu, we asked at one of the bus companies at station for student discount. I didn't have mine card with me, but they gave us discounted ticket anyway. At that time we paid 14 RM/per for a ticket to Miri, which is several hours away.
The small wooden boats are lovely and it is cheap way to get you across the river to nice villages over there. You will have to buy ticket at some of the piers and just point your direction. They will tell you which boat you will have to take. The price per person was 0,5 ringgit.