I too love Phnom Penh. Best pharmacies in the world. They say 1 in 3 is a rip off but I used two and they were both totally brilliant.
I can't remember the name of where the backpacker hostel quarter is, it might be Sisowath Quay looking at google but it might not be either. Regardless, you will get off a bus in PP and be ambushed by tuk-tuk drivers all willing to drive you straight there, it's the first place they will take you if you look young and backpackerish. As far as I remember it's a right out of the bus station, onto the main road and then a left. It's about 1km, certainly not far. The hostels are by the lake that was being drained when I was last there so it's probably gone now. Best value weed in SE Asia. Other drugs are available.
You don't need to speak Khmer. English is well catered for. Cambodian street kids are the most street smart in the world. Just one more dollar should be Cambodia's motto.