Just playing around with my first few flights.  I have a DJI Flamewheel550 with the APM2 controlling it.  I have got the rate pitch and stabilze gains working very nicely. 

Altitude control is really not very stable.  It wanders up and down quite a bit and seems to like to sag downward quite a bit needing me to bump it up all the time.  It has been quite cool outside (~5C) compared to being inside.  Does the barometer sensor need to acclimate?  I read the wiki on tuning but which gain should I attack first, THR_ALT_P?

I tried to set up failsafe to jump into Loiter mode but I have been scared to try it.  Holding the machine in my hand with a strap, the machine seems to want to take off upward and starts rocking back and forth.  I clicked on throttle failsafe in the radio config screen but all of the options below were greyed out.  Am I missing something?