Is there any fee for using this system, and can you set it up to be dynamic or do you have to set the % you're going for?
Crypto Lend does not cost whatsoever, and you can choose a strategy for the types of loans/% return. First you put your Bitcoin on one of the supported exchanges. In your profile on the exchange you can generate an API key, which you copy over to your Crypto Lend profile. This allows the Crypto Lend bot to loan out funds on your behalf. By ensuring "Withdraw" permissions are disabled when you generate your API key, you can have some extra peace of mind that Crypto Lend does not even have the ability to withdraw your money from your exchange account. You can always login to the exchange to see your loans, including the ones made by the Crypto Lend bot.
After copying over your API key and secret, go to the Crypto Lend "Strategy" page to Activate lending on the exchange. Every few minutes the Crypto Bot checks your account(s) through the APIs, and if there are funds in your Lending account on the exchange it'll automatically choose the best rates according to your strategy. I use the default strategy, sometimes the Crypto Bot takes an offered loan and other times it offers my funds as a new loan.
Also note that the "Loans" page shows averages for the day in GMT.