Does the website pay them their commission or do we pay them to moderate certain activities?
It's pro bono till you get to the staff level, to become a staff member you need to have a very high amount of reported posts, good accuracy in finding these type of posts and must do it constantly aka High Frequency of reported posts.
There is no place to apply for it directly, rather moderation is given to those who show up in Theymos top list for reported posts and offers to become a mod are related to good conduct here and duration of time on the forums alongisde the above criteria.
The money comes out of
Donations advertising to the forum, from ages ago. Round 161
https://bitcointalk.org/index.php?topic=1253630.0The
donate advertise button is the first ad you see when you scroll in any thread, the sponsored one.