Moving to Belgium Part 1

Hello, My wife and I are about 7 weeks away from moving to Brussels for her new job and we are incredibly excited! We like to be thorough. Very thorough. Thus, we plan on asking r/Belgium and r/Brussels a good amount of questions over the next few weeks about everything from electronics to banking to pet food.

However, let's start with some easy questions:

1. What do utilities actually cost? What might utilities run for a 70-80 m^2 apartment in Brussels? Electricity, gas, and water.

2. Would it be better to learn Dutch/Flemish or French? We plan on living in Belgium for a long time and languages are fun! They aren't too hard for me to pick up either. I've started with Dutch/Flemish and I am picking it up well, but I get this feeling French might be more useful and helpful.

3. Dutch vs. Flemish? French vs. Walloon? Give me the breakdown of when to use each term so I don't insult anybody.

Thank you for your help!