what are the leasing rights for leasing a beat (instrumental)?

Answer 1

In order to get permission to use someone else's music, contact ASCAP (ascap.com), BMI (bmi.com) and SESAC (sesac.com). They are the agencies assigned to collecting fees for musicians. Musicians, typically, only belong to one of these, but you will find them on at least one, and can negotiate the fees through them.