Just to be clear, those questions should be posed to your reputable and experienced systems installer; you’ll get a lot of opinions here that will likely be valuable, but the purpose of the Community is not to provide compliance review, as noted in the Community Guidelines, particularly because safety regulations in Belgium are not necessarily the same regulations as exist elsewhere in the world.
If you need to find good installers there are no shortage of them, and dealers as well, where you are; you can find them through Victron’s “where to buy” map, which lists both installers as well as dealers and distributors, many of the latter of which can give you recommendations for local installers to be sure to steer you straight and in compliance with your local regulations.