New Landlord - Do I give existing tenants new leases

I'm closing on my first duplex! Yay! Do I have to give tenants new leases with my name as their new landlord or can I just leave all as is, go introduce myself and tell them who and where to send rent?

Also, it's owner-occupied so one tenant was notified during escrow to vacate. Does anyone think if I come over with a gift basket and a $200 gift card as a "sorry you're getting pushed out" it is a gesture too much or unnecessary? What is the usual protocol for a new landlord of existing tenants?