But what's next? What are the next stages of the process?
theymos will PM you and state that you have been made a merit source.
If the candidate gathers a lot of positive comments, is it enough?
Does it have to wait until there is a free space among current merit sources or he can be chosen for an additional source?
Are there any rigid rules?
No rules, as far as I am aware. Some users have been made a source after 10+ pages of positive comments. Others have been made a source after barely any replies on their thread. There is no stated "limit" of merit sources, and nothing theymos has said has ever indicated as such. When new sources have been appointed in the past, the total number of sources has simply increased. Each merit source has a different monthly supply of sMerits, and on some occasions when appointing new sources, theymos has also altered the amount of sMerits some sources receive depending on their individual usage.