It would be nice to customize the options. For example - some staff would prefer to only get same day notifications

I agree 100%. . If our staff got notified when clients book in and cancel, not only could they adjust their schedule accordingly but we could contact clients from our waiting list and get them in sooner.

I would like to get an alert only when it has passed the timeout phase and it automatically cancels. Those who pay the booking fee or are confirmed should be the only texts sent.

Yes

Yes

Absolutely I think essential on an app