Nearly everyone is hooked up electronically.  

Single bank account, single quickbooks account handles my 8 properties fine, all the reports and income statements are generated by property, quick books even has add ins for tenant invoicing so they can pay electronically.

I can direct deposit into the HELOC and write checks to pay bills, but I still need a checking account to transfer money electronically instead of what I really want to do which is to set up auto pay directly from the HELOC itself.

I haven't read that book specifically, but subscribe to his investment newsletter (part of the impetus to keep investigating real estate) and have seen that discussion before.

We also sent them a newsletter once in a while with tips on how to save on their water bill.

How I managed: collect all rent via Chase bank deposits (not everyone had a bank acct. for digital payments), electronic leases, and would have a list of vendors service the property if there was an issue.

I use electronic ones and don't give out physical keys.

She is older, her money comes in on the first, she uses money orders, nothing electronic, and is far away. 

The owner was old school, so I'd print stuff out for him.A lot of my contracts were just done electronically with techies or students in Silicon Valley.  

Ours also have the electronic fob as an option to get in, but you wouldn't need the fob system.