Improve "Send signups to" UI

Howdy, as title says i'd like to discuss a small improvement of the "Send signups to:" UI.

Actually, admin can enter a default email address (backend settings) where to send notifications of signups of users, or leave it blank for no notifications.

Two things would make this process easier IMO:

1. %node_author email token [module settings]: the token could prepopulate the email field with the node's author email, saving him from filling it every time he/she creates a new event.

2. "Notify me about signups to this event" checkbox [node form]: it would let the organizer choose if to be notified of every signup to the event or not. If he selects the checkbox, then he will be notified at his registered email address.
Ideally it would be even better to dinamically show/hide the prepopulated email adress field when he opts to be notified, so to let him edit email address in case (jQuery).

A customer has asked me to make Signup simpler, so i might contribute a patch in case this is considered useful for others. Any thought appreciated of course!