Whether you prefer to read hard copies or listen to audio books(my preferred method), here are a couple on the topic of Wholesaling.The Ultimate Guide to Wholesaling Real EstateThe Beginner's Guide to Wholesaling Real EstateBigger pockets also has a book on the Subject How to Wholesale Real EstateHope this Helps and gives you somewhere to start.

If so, what have the lenders you have spoken with so far said about the minimum down payment you have to bring to the table? 

What are some strategies and methods that have worked for you guys to find and connect to/build relationships with other investors as a beginner in real estate?

I am wanting to learn more about the BRRR method, wholesaling, and building passive income through real estate investing. 

The tenant has the utilities in their name and the gas was recently shut off for non payment since September.

They are asking for 20% down and a 3 year balloon payment.

.$690k - $336k = $354kDown payment = $354k x 25% = $88.5kThe house looks like it was bought at $450k, so I am assuming that I will need to come up with around:$690k - $450k = $240k cash in addition to the down payment, Bringing the total to: $328.5k for cash to seller and as 25% down-payment based on the above.I hope I got all of the calculations correct, and honestly, the more I dive into it, the more I don't understand.

Never hold a house that has no payment attached to it.

@Jack BergThere are 3 main parts to a seller financing deal: down payment, interest rate, and price (4th would be the term).

They are looking to either keep it as a rental or occupy and rent out their current property.I understand the large risk of buyer non-payment and activation on due-on-sale clause.