in this sentence,"菜" means all of the "meals" on the table,not only vegetable dish.the sentence“is there any rice left”is right.the whole sentence means that you think the meals that are tasty,and you want to have more. "还有"——also,still,furthermore,in addition,besides,as well.all of them are ok.

IN THIS SENTENCE,IT ALSO CAN TRANSLATE AS "HOW ABOUT"

有，你要几碗

I agree with rex-wang's explaination for the first part of the sentence. "你做的菜真好吃" can also be translated to "The dishes you cooked are very tasty". "还有米饭吗？" can be translated to " Is there any cooked rice left?", and it implies that you want more cooked rice.

Yes," You make a really tasty vegetable dish, is there any rice left?" is right! 还有 sometimes mean "also" or "besides" ,it's depend on the sentence,i think.