No problems on the tips.
Either write cash on the receipt and leave cash, or carry a credit card or you can charge it to your room, set up room charging when you check in.
The server will bring two slips to sign, 1 for the plan, which should read $0.00 and one for the tip.
Meal ticket will give totals and suggested tips 18% and 20%.
BTW my meal plan for 4 was $971.02, my resturant and QS meal totals without tips was $1364.35. So it is worth it, I suggest booking ahead and going to more character meals/shows. I had 8 meals left over, yet we left Disney @ 6 am Saturday and drove home.