Making a MU comes down to several key areas:
- Direction - the overall theme and hooks of the game. What it's about and what the players are going to do.
- Grid
- Code
- Information (theme, setting, groups/factions, etc.)
- Work
It sounds like you have 2 & 4 pretty well covered.
5 is just a matter of ensuring that you have enough help to make your vision fly. It's certainly possible to run games by yourself if your Direction is set up to support it. Multi-faction/antagonistic/heavily-plot-driven games will require more staff. So think about what you need and then recruit as necessary.
1 & 3 go hand in hand, because your direction is going to drive what code you need. A Star Wars game centered around smugglers and Hutt crime bosses can probably get by without a coded combat system. A Battlestar or Gundam game with huge battles every other week would struggle without one. What kind of game are you going for, and what type of code will it need? Then you have to ask what kind of code you're able to develop in the timeframe you want. As @mietze says, Ares comes with a lot out of the box, but it won't fit every game. If it's not the right fit for you, then you have to figure out what platform is and then secure the coder resources necessary to build the game you envision.
Good luck!