If you have access to MLS or a title company connection, use that info to find out who has been buying homes in cash in your market(s). 

That way you have access to some quick capital for a purchase and rehab expenses.

There are other ways to access this without getting your license.Knowledge of RE in studying to get your license?

With gates on both side to give direct access to to the open field/park behind the duplex.

For example, that no more than 25% of the existing SFR may be demolished/altered to make way for say an access driveway easement for the new rear flag lot.

I would assume that agents in your area have access to that data on their MLS.

Also, providing internet access is also a sticky subject, if you had access could be a violation of their privacy. 

Also, interest rates are very low now, so it would be nice to have access to that money.

Then, you just continue the process of using the HELOC like savings and checking etc...Most primary First Lien HELOCs will give you up to 90% LTV on the appraised value of the house, too, so you'd have access to more cash.

If you can't find what you're looking for, try the BiggerPockets' FilePlace: https://www.biggerpockets.com/files It contains hundreds of files such as ebooks, checklists, and spreadsheets for real estate investors.