Americans usually do not say that they are looking for the toilet when they are looking for the bathroom. That would be a tabu. "Going to the toilet" in the United States means urinating or defecating. 

"Could you tell me where the bathroom is?" is a proper question.

"Could you tell me where the washroom is?" is also proper.

"Could you tell me where the restroom is?" is also good.

"Could you (or would you) tell me where the powder room is?" is very polite.

NO!  "Could you tell me where the toilet is?"        Yes, I can. It's in the bathroom!

A full bathroom has a bathtub and/or shower as well as a toilet and sink. 

A half-bath or half-bathroom only has a toilet and a sink.

Most bathrooms in the United States do not have bidets.