If the whole idea is to reward quality posing users, and slow spam down. Then farming for it, or giving it to someone just because they are your friend should be against the rules, however would be hard to prove. So it is likely just unethical.
Trading merits to your friends is not against the rule.
I haven't read it here
https://bitcointalk.org/index.php?topic=2818350.0As long the post of your friend is qualified to a quality post, giving merits is not an issue.