I am most interested in house hacking and multi-family properties but would love to learn about all aspects of real estate.

It's essential to clearly define your goals.

Tried QuickBooks and didn't like the Customer/Vendor aspect for properties and tenants.

The participation must be regular, continuous, and substantial as defined by the IRS.

You make the payments to the lender.Oh, and just in case, there are more items to know about when considering a "sub to" transaction but this is just a comment on the payment aspect. 

Also make sure to consider all the aspects you can including the tax differences. 

I’ve recently finished reading J Scott’s “The Book On Flipping Houses” and found it to be extremely helpful in understanding most aspects of a fix and flip project.

I would get an attorney or title company involved to create your loan documents to ensure they comply with the law and cover all the aspects you need.Another method that is likely your best bet to take on investors is to create a joint venture (JV).

I'm very new to real estate investing and I'm looking to start in the wholesaling aspect of it.

This will provide you two benefits:1) Help you better define the position, so you can hire a better matched person2) Make training the next person easier