My coach, the pump works off the 12V "starter" battery..but the control pad runs off the 2 6V coach batteries.
Mine says to raise the front jacks first, then the back,to level front to back. then level as needed using the bubble. The rear jacks do the side to side leveling, the front jacks are the "slave" jacks...following the rear side to side jacks. Then...fine tune after that. Be aware, tho, that extending/retracting any slide(s) will change the level. So...my opinion is to have the slides OUT....THEN put the jacks down.