Powerapps small project

I want to make a simple vacation request in MS Teams, with authorization rights set in Powerautomate.

FASE 1
-User (with unique color-code) selects start date, end date, type of vacation, and if it is whole day or part of the day
-Send email with request to 2 managers
-Managers can approve/reject
-Users can read-only requests of other users
-show in calendar

FASE 2
-give each user total days, and show balance of days per user