Tidying beard by trimming allowed?

Muslim men are told to leave the beard and trim the moustache. There is some discussion whether you can trim more than a fistful of the beard. Besides that can you trim the hairs if they are sticking out or growing unequally for example? Or are you just supposed to leave and keep as "tidy" as possible by combing and using beard oil to press the hair together? Secondly can you remove the hair on the neck? Does this constitute the beard area?