"And where is the toilet?"
Translation:А где туалет?
"И" plays a different role. When starting a sentence, especially a question, it usually means "so".
As for «а», it often starts the questions in colloquial Russian, just like in this sentence. I guess, it is less intrusive this way because you are trying to tie up the question to the previous conversation ("by the way, there's a thing I want to ask").
I disabled the translation from English, anyway. Does not seem fair to people who are just learning.