You can set up individual shipboard accounts if that's your wishes. Just make sure all three are at the counter at the same time and let the represenative know when you check in.
As for Speciality Restaurant surcharges, here's the basic setup:
Le Bistro $15
Cagney's Steakhouse $20
Il Adiago on Sun, and the Kahili on Aloha are both surcharge Italian restaurants, $12.50.
Note: Other Itlaian restaurants on all other NCL ships are free.
Additionally, sitting at the Sushi Bar or Teppanyaki Table in the Asian restaurant has an additional, around $5 surcharge. Also, some rather large menu items at Cagneys and Le Bistro have a small extra charge, examples being Surf and Turf and the Tenderlion (double entrees or size).
Hope this helps!