Hey Audrey, great questions! I'm not super familiar with the real estate market in Couer d'alene like I am with East Idaho or even southern Idaho or the Treasure valley. But I do know it's a beautiful area!
It is NOT required by law to sign a buyer's agreement before you start touring homes. It IS required that you at least sign a RE-05 (Prior to Showing Agreement). Here is what that looks like: https://idahorealtors.com/wp-content/uploads/2024/07/RE-5-Pr.... It is my opinion that you should sign a RE-14 at some point in the journey and definitely before putting in an offer. This requires your agent to truly be YOUR agent and promote your best interests and keep your bargaining information confidential. Without it they are not legally required to do that (look up the "blue brochure" https://dopl.idaho.gov/wp-content/uploads/2023/10/irec-Agenc...). It is my practice to sign a RE-14 early in the journey, but in good faith I put a $0 fee to exit the contract. I want to earn my clients business and if for some reason they decide the relationship isn't working then they should walk away (but don't leave your agent high and dry haha).
Commission is completely negotiable. I think 3% is a very reasonable commission for a buyers agent, but it's whatever you negotiate. In my side of the state it would be very common for a seller to cover that kind of commission for a buyer's agent.
Don't shy away from dual agency in my opinion. If they're brokerage is of any size, you will likely run into listings from their brokerage and you don't want to exclude yourself from those, especially if you like the agent you are working with. Just have an honest and open conversation with your agent about this early on.
Hope that helps in some fashion!