It’s meant to periodically scan the locations for new content, so yes, newly added ones will be downloaded as well. By default it scans every 10 minutes!
As for channels, it supports any web page that yt-dlp can parse as a playlist, so more than likely whatever kind of page you’re thinking of will work as well!
yt-dlp is impressively compatible.
You could try out something I whipped up for this and see if it works for you: https://github.com/MattMckenzy/ToothPick