I have several group and repeat sections within a form and have them set to compact so the user can access whatever portion of the form they need quickly and efficiently. Opening the group is easy, but there should be the option to close that group when you get to the bottom of it without having to scroll up again to find the arrow.
For the repeats, when the user chooses to add a repeat there should be an option for that to automatically take the user back up to the beginning of the repeat so they don't have to scroll up to find where it begins. This would be very useful for longer repeats.