I've a couple of questions here:
1) Say I'm a waiter in a pizza restaurant, and I want to ask patrons if they want me to cut the pizza into pieces and serve to everyone's plate, should I say: "Do you want it to be served on the plates?" And if they say no, can I say "Help yourself?" (sorry, it sounds silly to ask this but I'm not a native English speaker)
2) What should I say if I want to ask patrons whether they mind me send the bill to them earlier (ie they can enjoy their food but they need to settle the bill earlier).
1- You could, but I wouldn't. I'd just say 'enjoy your meal'. They should know what to do if they don't want to be served.
2- Just say 'I'm afraid we have to close the till soon, you can take all the time you need with the meal, but would you mind if I brought the bill to settle?' Then thank them and smile a lot.