Get service records if your friend has it, otherwise see if your local Infiniti dealership can fill you in on any recalls that may be needed. At 80k you should consider rear diff fluid change, serpentine belt, and possibly a brake fluid change if it's dark. You can consult the 2012 Service and Maintenance guide to see if you want more things done. If you don't have that guide they are listed on the right-hand side of this page: https://infinitig37.com/sedan.html
Most Nissan/Infiniti techs say the CVT is trash so I would hope the 7AT is better.