I'm looking for visual reference material that would provide an at-a-glance display of at least the essential puzzle pieces to a real estate transaction specifically concerning the entities/parties involved & their role.

They are a critical piece of the puzzle. 

I feel like I'm missing some piece of the puzzle

I am trying to puzzle together different ways to purchase another property by the using HELOC.

@Gino Barbaro, great thread.Just to add my perspective, if you don't have a deal, don't have money, don't have experience, don't have financing, don't have a team, don't know a particular market, etc. there are many people on this forum like Gino who have these puzzle pieces already put together.If you are just getting started and want to get in the game, figure out a way to add value to someone else who has what you seek or want and make it a win-win situation.

There are so many moving pieces to the puzzle.

An agent is key too and yes speaking with a professional for financing is the key to the biggest piece of the puzzle.

I will calculate 10% approximately the cost to resell the house once I buy it on seller financing, my reasoning for this is it's going to cost 6% for the agents commission, 2% closing cost, and 2% for ancillary costs to re sellSo here are the pieces of the puzzle: 10% costs to resell or 80,000+10% rehab which is 80,000, + 8000 for interest  +25,000 for my fee to do the joint venture with the seller.If you do this math, you're going to find that the seller is going to go to much more money than the wholesaling offer.And we as real estate investors avoid banks and make $25,000 income to "help with seller with a house that's  really hard to sell"@Bronson Kane

One lead is puzzling and I don't think the deal can be done but any opinions will be much appreciated.

The traditional way would be to hire, train, and keep managers or employees that you can fit into the puzzle that is your business.