Eating & Drinking @ Melia in Nassau ?

We will be taking the jitney over to Melia and even though I've been there before, I do not remember eating there. I know that O'Grille is there but I was wondering a few things:

How much for a sandwich is it is large enough to split for 2?

Also, where is O'Grille on the property ?

Also, I seem to remember people say they've purchased snacks in the lobby area ... What is that all about ?

Also, I think I over-tipped last time for drinks. Is a gratuity already added in the drinks at the beach bar?

All opinions/experiences are welcome. Thanks! :)

The Melia website has photos and details about their restaurants.