You can start with a CAR purchase and sale agreement and incorporate a single addendum to include all of the contractual requirements for the assignment/wholesale transaction.  

As for management, I'm not sure you'd need a platform to manage a single property.

., "I will buy at least one single-family home, duplex, triplex, or fourplex before the end of 2019") and then do it.

Once it is up and rolling it is pretty easy for a single property.

I'm looking for options for possible next moves for one or all three of our single-family rental properties in the Austin and San Antonio areas.

Get pre-approved for a buy and hold loan- It could be multifamily, single family.... depends on the market3.

Single homes, duplexes and multi-family property is what I'm looking for. 

It can still work, but focusing in and around your backyard is smarter as long as you don't rush to make a net negative deal which you aren't doing.If you are nearby, I would skip property management for a single-family home.

I am looking to target younger families, single family homes to start.

(Note: you said "single" which you are not.