Do I need to make a contract with a friend for a sublet?

Hi! My roomate told me she is not resigning for our current apartment. Our lease cycle begins on Nov 1. I have a friend of a friend who is interested in taking her spot. I chatted with my landlord and my name would be the only tenant name on the lease and my agreement would have to be seperate with my future roomate. I want to protect myself but want to start off on the right foot and be friends. Should I ask her for a a rents worth of deposit in case she backs out / is that normal for a sublet agreement? Any agreements you recommend I base my contract off of? What questions should I be asking her in the tour? Never been in this kind of situation, all advice is appreciated!