https://yunohost.org/en/install/hardware:vps_debian

Set up Yunohost and then use it to install mastodon. You can do most of the work in a GUI. Also Mastodon takes a good while to install on a smaller VPS so once it starts installing, give it awhile.

Zero. You would have to code your own moderation system into mastodon because there is zero control on specific posts in mastodon because it is designed to be open and free.

You’d be better served with something like Buddypress since it has built in post moderation as a part of WordPress. There is an activity pub plugin in WordPress granted I haven’t managed to get it to work with Mastodon yet.