First time buying a multifamily - Process of getting tenants to pay me?

[Steve Candor]

So once I purchase the property (or prior?) what do I do to get the tenants to start paying me the rent instead of the older landlord? Do I draw new leases up with each one (they are already on leases) or just tell them the new address to mail it? 

What about inheriting section 8 tenants? Does it take a while to have them start writing me checks? reinspection?