It consists of two contracts : a library and a "normal" contract. Using this method, it's cheaper (53%) in terms of gas used to deploy. You will have to search by yourself on how to link the library code into the other contract.
You are responsible for the use of the code. You are responsible for auditing the code.
When setting the fee, it has to be calculated by yourself using the following formula : 1/fee.
Example : 1% fee -> input = 1/0.01 = 100.