Yes, most people have names like that to easily show their character's gender, age, or species. F for female, M for male.
Where you in a private/downloaded map when they were roleplaying? Since as far as I know, general chat doesn't work in the public maps. But, the roleplaying varies, for a 1 on 1 roleplay, players would use whisper chat or for a roleplay for only certain people, they would form a group and roleplay in group chat. I'm not a big roleplayer on the game myself, so I'm not sure if people prefer for private roleplays or not.