Living areas in and around Brussels are hit and miss sometimes, it can be quite hard to find decent priced places. A lot of expats I know choose to move out of Brussels to nearby towns, Leuven or Mechelen are examples, about a 20 to 30 minute train ride to/from Brussels (North station). The public transport works but always calculate time for delays, they are more common than bread unfortunately. Finding a decent area to live in Brussels requires a lot of research, some areas, like Elsene, are great to live in but some parts of that area are also to be avoided.
As for tech scenes, there's plenty, the Meetup app might be helpful for that.
There's so much I could tell you, as I myself live in Belgium and have been working in the IT scene for over 17 years, most of that in Brussels, so if you have questions or want to have a talk once you're here you can reach out to me via my profile.
Welcome to Belgium!