New used Camper

I just purchased a 2015 T@b Max S, which was winterized and I plan to use it this weekend.  Other than the valves next to my Alde 3010 heating system, is there any others that I need to change.  I probably won't use the camper again until August.  Do I need to winterize it again?  I was told that there is a drain by the rear stabilizer on the driver's side.  What is this for?

Joel