My question is what is the most cost efficient way to use the equity to put a down payment on a second investment property?

Sure, if you hire others who have the licenses/certifications that you need in whatever area you are in.You'll probably need a licensed architect and/or engineer for the plans, a licensed GC to pull the permits, licensed plumbers/electricians/HVAC contractors to do the mechanical work, licensed testing companies to do the various energy efficiency tests, etc.Hire people who have the appropriate licenses, and you should be good...

I enjoy the challenge of trying to make properties run efficiently and do so at scale.  

I am also planning to test this as my portfolio grows so I can be as efficient as possible. 

If your furnace is in the attic it is not going to be as efficient as it would be if it were in a conditioned room.

I have to agree that the cost of a closer is a whole lot cheaper and more efficient than getting a bunch of security cameras, spending time trying to find out who left the door open and then changing the lease up.

Updating my property management software to extract and categorize expense line items from receipts to more efficiently allocate rental income dollars to income tax reserves.

In the former situation, you should expect to have about 30k cash (unless you have investors or plan to owner-occupy) and can probably only find an efficiency condo in an outer part of Austin.

(I'm assuming this would be dramatically more cost efficient solution and I could ultimately gift my parents the originally intended "down payment" money over the next few years (depending on gifting limits). )D) Parents Gift the Property to Me?

Direct mail is the best/cheapest/most efficient way to reach motivated sellers.