No, on reddit you are subjected to the reddit administrators their policies. You have no real control. The user interface is also awful if you're interested in content older than a day.
And the voting system builds toxicity for smaller user numbers than should otherwise be needed.
It's not that different from Discord; unless you run the platform, there's always the risk of deplatforming.
Mostly, yes. Particularly in the terms of "Discord-difying forums". But you cannot have multiple subforums for your community on Reddit (unless you do something weird with subsubreddits, but those won't be clearly visible). Discord allows you to have several channels. Additionally, I'd like an alternative that isn't threaded like Reddit and HN. Threaded communities have their place, but classic chronological topics also do.