For example, we've recently taken over marketing internally because the property management company was not experienced enough in using the newer advertising methods we need to pursue.

Urban Lot Splits (ULS) allow you to divide a lot into 2 parcels, and Multi-Dwelling Unit Developments (MDUD) are allowed up to 2 units per lot.

You’re not going to find a safe way to do what you want unless you or the “buyer” has enough cash to pay off the note. 

Out of curiosity would anyone be willing to share any experience with non-paying renters who've vacated the property prematurely?

Work backwards from your $300,000 annual target to monthly say $25,000 per month.  

Often the best risk, hassle and tax-free approach is to pay down debt.If you have a car note, credit cards, etc pay those off first. 

Agent gets paid from the net proceeds unless the seller is unwilling to pay the buyer agent fee/commission, which in this case you do not have an agent; that agent would ask (if they were representing you) for the buyer/you to pay them their commission from a buyer broker agreement (if the seller was not paying commission).So it's the same difference, the seller will pay it (2%), and the agent will not come out of pocket for it.

It’s waaaaay easier for a company to fail or be unable to pay rent than you think.  

My goal is to purchase 15 units in the next 5 years, and produce a cash flow of $20k per month within the next 10 years.  

I have never been disappointed and have actually thought he pays an extreme amount of attention to my needs for the price he charges.