You're fine streaming at the same time as long as you're all under the same public IP address. As long they detect only one public IP address at time it'll be fine. If an account is being accessed from more than one IP simultaneously than you're going to have problems. Also you don't need to use VPN with Real-Debrid. But if you ever decide to do so again make sure nobody else is accessing your account.

You have to get an invitation but it's not too difficult to get one. They're offered quite frequently on r/UsenetInvites, though you have to be quick.

Unfortunately, the discord is restricted to Snahp members. It's only distributed on the forum and isn't allowed to be posted anywhere publicly outside of the forum. Anyone who joins the server and asks for invite codes is banned. Without personally knowing any members, the way in is pretty slim. The only other option would be to find someone who is a member, message them privately, and see if they're willing to donate on your behalf (donations are done in crypto).