Muang Phonsavan Transportation

That is just another typical bus station in Laos: few km from the city so you'll need to take a tuk tuk to get from/to there. We had to pay 15000 KIP for a ride to town and we didn't really have much choice unless we'd walk 4 kms with our bags.
Once weekly - on mondays - there's bus directly to Ha Noi, leaving early mornings. Few days weekly to Vinh.
Every morning at 8 am you can take mini bus to Xam Neua, 60 000 KIP for about 8-9 hrs long travel. We didn't go to the station - we waited in town for bus to pass the old bus station, then we got on. If you ask in the GH they tell you to go to the station, but it's no need (for this direction) as it pass the main street and all those guesthouses. The scenery between the two provincial capitals is one of the nicest in Laos and it's very scarcely populated, with lots of rain forests and hills. The bus will stop at the provincial border town for a lunch, somewhere the half way.