Hello

Merit in this forum is like an "award" that is given to you by other members here. What it is for? The actual function of the merits here is to rank up your membership once you accumulated certain amount required for each rank. In your case, you if you were able to get to 10 merits, your rank will be changed to "member". Ranking up is not just based on the merits you received though, you also have to have a certain amount of Activity that is required to rank up.

Yep, it gives some advantages, but it is somehow subjective (for me). One advantage is that if you join campaigns, it is more likely that you'll be paid higher compare to the lower ranked users. Also, some could see you a good member of this forum because of the merits you earned. It sometimes and somehow attracts trust of other users.

Merits are earned through other users giving it to you, maybe for the quality of your post, uniqueness, helpfulness, etc. Giving merits is subjective, so anyone can give merits on anyone they want to send to as long as they have sMerits left.
Given that even though a user posted a funny or a "dumb" post, he/she can still earn a merit if anyone likes to give it to him/her.