No, you can use permission plugins like PermissionsEx, Luckperms, etc to grant certain perms to the player using ranks, I recommend watching a tutorial on how to use them (Luckperms is more user friendly)
does it say the server is whitelisted or full when you join it? also some servers block bedrock players, so if you're on bedrock thats most likely the case
1.18 support for minehut will be added very quickly, plugins? no, that will take time, but the most used plugins will most likely be updated first so you should be fine if you wait a little bit for them to update
believe your server has an outdated plugin which does that, try /minecraft:ban instead (minecraft:ban doesn't provide tempbans though, so i'd suggest getting a working plugin)