Hey sorry for not getting back earlier. Thanks for joining. What's your username? Feel free to say "hi" or ask whatever if you're still there. I'm just a guy who's interested in programming. I'm in no way affiliated with Discord or Wolfram Research at this time (I did work on a short term research project with someone from the company a little ways back.)
There's Discord channels for other languages but there wasn't one for the Wolfram Language yet. I am hoping that people might just share ideas about the language, or ask and answer questions (I have answered a few so far.) Perhaps people will want to work on projects together (I know I would.)
Also if people are interested in talking about Wolfram Alpha or A New Kind of Science (I've read it all the way through twice plus flip through it now and then) I would for sure be interested in talking about that. To answer one of your specific questions, as far as I know, Discord can accommodate as many people as whom join, so no limits as far as I know (no plans to set limits myself on user number at this time.) If you have any other questions feel free to ask on there or post here again!