Know-How Exchange : Advertising/PR

We are a small business that is very shortly going to be rolling out our service nationally. It is complicated to explain why, but my focus has been on readying the tools on our site for the rollout, and not the implications for advertising.
We are starting to get inquiries from ad agencies whereas before we only sold direct. We don't use any kind of collateral material or sell sheet. We just tell people the price and send them the contract. My boss is fine with this.
I am way not fine with not being able to represent our company in the professional language that agencies speak. Any book or crash course available on how to put together a "Why us" sheet with our hits per day, etc. How do I explain, in their language, that we neither add in commissions nor do we discount for people who do business with us in another way. Etc, etc. Thanking all in advance!