The Naluang Bus Station is located in Luang Prabang.
It looks like it's in the middle of nowhere but it's only a small bus station in a large dirt area, there's also a number of restaurants and shops that sell snacks and food nearby.
There are two types of buses in Laos, the VIP bus and the "normal" bus. The VIP bus has air conditioning, more comfortable seats and most of them have TV and a toilet on board. Drinks and light snacks are also served on some trips and there are also VIP double-decker buses in Laos. VIP buses always leave at their scheduled departure time but normal buses sometimes wait for more passengers until it is filled to full capacity. VIP buses also arrive to their destination faster than normal buses because the normal buses stop regularly to pick up more passengers along the way, where as VIP buses go non-stop. The first to get on the bus for a normal bus and the first to purchase a bus ticket for a VIP bus gets the best seats.
There is no limit to how many people can board a bus in Laos, basically they allow anything that fits in. As you can see, there are passengers sitting on the walkway and the front of the bus next to the bus driver and there was even a dog on this particular bus. Yes you are allowed to bring anything with you, even a motorbike or ten bags of rice because there is no weight allowance but you may need to pay an extra cost.