Drive on the right.
France - autoroutes great, not so easy to pay if you are on your own. Driving standards ok, speed traps proliferating, and do not drink drive (lower limit there).
Belgium - driving standards horrible, watch out for people swerving in front of you with little consideration. Cruise control not permitted on busy motorways. Easy to get through Belgium rapidly, as Germans have shown many times. Service stations uniformly horrible.
Holland - petrol prices horrendous, roads ok, service stations ok.
Germany - remember that unless a speed limit is posted on the autobahns it is unrestricted, and fast driving is great. However, this requires absolute discipline and concentration and you must pull over when you overtake, a German behind you will sit inches from your rear bumper at unfeasibly fast speeds if you don't. Braking at fast speeds requires a lot of alertness. Traffic levels can be heavy, and two lane autobahns can be a trial when busy.
Driving laws - check in a Michelin atlas or similar. Take a hi-vis vest, spare bulbs etc.
I do a lot of continental driving, and it can be great fun. Enjoy.