Who pays the agent's commission?

It is always the seller or landlord that pays the commission for both the listing agent and buyer's agent.

Do I have to put 20% down for my down payment?

This is a common misconception. In fact, most loans only require 3-5% down depending on the loan with the exception of VA loans which can be as little as 0% down. Take a look at my "Down Payment Assistance Programs" tab under "Buyers" for programs that can help. You can also contact your lender for more information, or if you don't have a lender contact me and I can give you some options.