Based on my experience buying three properties and selling two off them, the price will be expressed in dollars. Most sellers will only accept dollars..
Unless you buy directly from the seller, the buyer almost always pays a four percent commission and the seller often pays two percent.
An agent is not required. All they really do is get the buyer and seller together and take a commission for doing so.
Real estate agent will always show the exclusive listings they have avialble, but not many (if any) others.
Splitting a four percent commission kills the motivation to work with other agents.
That being said, In today's (nearly dead) market, you might be able to get an agent to accept three percent.