Elevator trimmer: some Cherokees were modded to have an electric trimmer on the LH yoke - it is a Godsend, but make sure you identify the circuit breaker if it is fitted!
Retracting flaps: I was taught on a Warrior (v. similar) to drop only 3rd stage of flap (drag flap) after landing in case of having to touch and go.
You might want to check whether you should start it with mags on Both or either L or R (I can't remember which). I've flown a 180 where it shouldn't be started on both - not sure if it applies to a 140.
HTH
SD