Much of the work is checking in on the threads, reviewing and approving posts and watching the interaction to ensure it stays friendly enough.
At times one needs to move threads and answer questions from members about comments or movement of threads. On rare occasion those interactions can become heated. I have never had what I would consider a heated interaction here. I have fielded questions from some members, and I believe that my responses may not have 100% satisfied them at times. Comes with the territory.
Typically to become a moderator, you need to have demonstrated time and commitment here. A track record of helpful posts over time kind of builds up a reputation.
By memory I had been a member for around 3 years, and had ~1000 posts when I became a moderator here. I don't moderate anywhere else.