There is some bad press about Puerto Viejo, but the area is quite safe. There have been some violent crimes in the past, but things have improved a lot since then. If you do not mess with the drug scene, you do not have to worry.
Puerto Viejo is a great place for independent travelers. In the town there is an ex pat community. Most of them are backpackers that came here for a couple of days, and ended up staying here.
The bus stop is at the entrance of Puerto Viejo, north of the town. In the area there is a bank with an ATM, and the town's post office.