The old 'priorite a droite' rule is now largely gone, and it applied mostly in France, much less anywhere else.
When it does apply it is not just on roundabouts, it is also sideroads both rural and urban. If there is a sign as you approach a junction with a thick vertical line (with pointed head) and a thin crossing line then you have priority. If it is just shown as a cross then it's anybody's guess. You develop a technique of looking at the end of the side road as you approach looking for a white (stop) line - or sometimes a line of triangles, not that the (french) locals take any notice!
As for somewhere to stay, a good place is Camping Blaarmeersen at Gent. It is a good site although access to some pitches with a long 'van can be a bit difficult in places. You may also need a long mains cable on some pitches. Facilities are excellent and spotless. There is a restaurant and takeaway on site, and a small but quite well equipped shop. Only down side is that it can be a little noisy sometimes as the city ring (road) passes close by.
Many find Gent more enticing than Brussels, but if you insist the St Peter Station in Gent is about 20-25 mins walk. The local bus service is about two minutes walk outside the site gates and will take you into the city centre where you can get a train to Brussels - don't drive there it's manic and parking is expensive, especially if you don't know your way around.
By road Brussels is about 40 mins to the centre, Brugges is about the same the other way, and Lille (France) is about 50 mins. The WW1 and WW2 battlefields are also within reasonable distances. Motorways are free in Belgium but it is illegal to use cruise control when travelling on them - although how the police would know baffles me.