I like the idea of using Fate mostly because it puts everyone on a level playing field giving them all the same amount of abilities and stuff. Although I'm not sure of how it will play out. When you're at a table using a system like Fate, when a roll is needed the GM just says so then you find the result and continue from there. I'm worried we'll end up in a situation where there's an exciting situation then we're just kinda stuck waiting for the GM to let us know the outcome rather than just deciding what works best for the story. I'd even be okay making a character with a preestablished system just to keep everyone even before proceeding to ignore that system for the actual RP.

As for Discord I've never had issues with a server, just make sure there's a meme channel for when people inevitably start making jokes