It would be a direct sale with no brokers involved. 

Is using a self-direct IRA to fund this venture a way to defer taxes until retirement ?

I agree with calling the city/county and finding out directly from them. 

I can help with pointing you in the right direction of some good resources to help you in your investing journey! 

Trump got significant tax reductions in his first term when essentially all demorats proposed tax increases.Of course, we don't want guess work, but we also don't want to ignore the direction that the tax policy will be headed.

When I purchased my first large apartment building my real estate broker called 18 different banks until we found one that gave me the loan and I saved more than $20,000 by dealing directly with the bank and no loan broker.Then, as time went by, I got lazy and found what I thought was a terrific broker.

while still trying to keep up with the competition Do you rely more on direct-to-seller marketing, networking with agents, leveraging platforms like PropStream and Batch Leads, or just by looking at a lot of deals?

So my folks that I fund do the normal stuff SEO  Direct Mail text and ( what I did) telemarketing. 

Microsoft Excel, and most budget or free online bookkeeping isn't going to cut it in this situation.For the rental properties you own directly, I often tell clients and prospects that a P&L in Microsoft Excel is just fine and a balance sheet is not necessary for tax purposes. 

I can help direct you to a few local networking & meetups for investors.