One benefit of giving ample notices has been getting the notice reciprocated from a tenant of non-renewal of lease (90 days).

On the other extreme, for a (median) $382,650 purchase, rented at $1,400 /month rent, a mortgage at 0% down, 5% interest fixed for 30 years, the interest payment alone starts at $1,594 / month.

Hi, if I wanted rent payments ACH deposited like clockwork from tenants every month, what would I need ?  

Keep solid records of every rental money move, get cozy with the right tax forms, and think about making estimated tax payments throughout the year to dodge penalties.

Can he comfortably cover the payment is he gets a POS tenant? 

Non-tax advantaged investing (stocks, lending, etc) in a retirement account. 

As long as the home appraises the equity should count as your "down payment". 

Can they do a 1031 exchange and use their funds towards the down payment of a property and have their daughter take out a loan alone for the remainder of the purchase price (since she has a higher credit score)?

You're right or just pull out a HELOC from my first property for a down payment.

Your DTI for a mortgage is based on the mortgage payment.