Some benefit for the First 10 people to sign up
>>> Not necessary. Songwriters WANT to have their songs heard. And you are leaving out guy #11... why make him feel bad? A well run writers night is its own reward.

Use a triangle chine or cell phone timer to indicate when time is up
>>>> Bad idea. No one likes to run against the clock while performing. A 3 song limit is a better way to go.

Promote interaction among the regulars get-togethers after the event or another times
>>> Not a good idea (imo). A good percentage of songwriters are introverts (it's why they started writing songs in the first place). People want to go to a writers night, perform their songs, get some appreciation - and then go home...


Make newcomers fair welcome how?
Experiment with time limit is it better to have a five minute time then repeat performers
>>> treat everyone the same.

Social media mailing list Facebook Twitter possibly post pictures from the event on the web and encourage performers to do the same
>>> good idea

Sometimes have a pro perform or the host does established pieces as well as tryouts
>>>> the "pro" idea is great. the "host" perform?... no one likes that.