While the two cars may be good for keeping your large group together and they will be useful for discovering the Netherlands countryside (how many days for the countryside in your short 4 day trip?) they will be very difficult to use in Amsterdam, Brussels and Bruges (Brugge). Parking in Amsterdam is very difficult - narrow lanes with canals at one side, many many bicycles who have the right of way and take it sometimes when they don't, and trams who also have the right of way. In addition to being very difficult it is also very expensive when you do find some. The odds of being able to park the two cars close to each other are low.
Parking in Brussels is also very difficult, and the kerbs are both high and sharp. Brussels drivers as a whole are not known for their driving skill. There is little or no free parking.
Parking in Bruges (Brugge) is very difficult. There are two major underground carparks and a large one at the train station, but if you are going to use those you may as well use the trains and buses - you will have to for part of the journey. On street parking is difficult because of the cobbled streets and narrow roads and the lack of spaces. There are two zones, blue and white, you will want to know what your accommodation suggests or if they have a friend with a space for rent.
How large is your group?
You will find that not knowing Dutch is either no problem at all or only a very minor one.
Dutch motorways are crowded and not always fast. Do also remember that it was the Dutch who invented the automatic speed camera, and they have plenty of them at work.
Antwerp (Antwerpen) is known for its traffic snarl ups. There are two possible ways around and through Antwerpen, the clockwise way involving tunnels with tolls and much further around, but often faster overall, and the anticlockwise way nearer the centre but often very slow. I have never even attempted to try to park in Antwerpen.
I wish you good times on the trip and pleasure planning it.
