Tenants are going to try and take advantage whether residential or commercial asking for concessions.

Did the rental market collapse with renters taking advantage of falling interest rates to become property owners?

Would you keep buying propertys and take advantage of the opportunity or wait to see how the market behaves?

People still need to be able to afford the down payment to take advantage of low rates and I don't think as many people have that money.

Do you believe the Fed cutting interest rates to near 0% could be taken advantage of here? 

Biggest advantage on HELOC rates?

In addition, if you are self-employed with no full-time employees you may wish to consider opening a Solo 401k instead of a self-directed IRA as it has several advantages over an IRA LLC such as much higher contribution limits, direct checkbook control (i.e. no need to have the account at a specialty trust company), ability to take a 401k loan, exclusion from unrelated debt finance income tax with respect to investment in real estate acquired with non-recourse financing, etc.In addition, please note if you purchase debt-financed real estate with your IRA, unrelated debt finance income tax should apply to the income attributable to debt-financed real estate held by your IRA.

If your ending up with the same number of units in the end is there any advantage to one vs the other?

Congrats on the job and on your desire to be an investor.There have been some very insightful posts, but one thing hasn't been mentioned - the tax advantages of owning a rental.

Keep the end goal in mind, and take advantage of this opportunity to maximize your ROI!