You can use the ASCAP and BMI websites to search for ownership of copyrights.

You have to pay a mechanical license fee to the author of pre-published copyright protected material IF you are recording and publishing that material yourself. If you are recording that material for demo purposes, not creating a high volume of copies (eg 1000+), and not seeking profit from the copies - you are most certainly NOT liable for paying mechanical license fees.

Go to the library in your town and get the copyright forms. The rules are explained in the forms.