Just a few additional words of encouragement.

There is more to the formula on how much you can bring in, assuming you're self-employed.If you're an S-Corp, you can do the 23k as an employEE, then an additional 25% of your salary on top of that, with a maximum of $69k total. 

If you are buying a 2 unit building, especially if you are planning to buy additional investment real estate your best bet is to work directly with the smaller banks/credit unions in your community if that's where you are purchasing or in the area where you plan to buy.

Many never bother to even get their licenses.A couple additional pros and cons:1.

Unexpected Costs: Real estate has a lot of additional costs that aren’t always obvious.

@Greg Hammond If you decide the property is no longer worth holding on to and you decide to sell, in addition to the capital gains you want to consider depreciation recapture as well as any closing costs and commissions.

@Albert Bui @Carlos Valencia There is no offset when you live in the 2-4 unit remember its a full HIt to your monthly PITIA and yes you can use the rental income but only as an addition to your qualifying income, you're still taking a FULL hit on the PITIA.Its only offset when you vacate or move out or it has already been converted to a rental (pure investment/non owner property). 

If you will be purchasing materials those cards offer some discounts and in addition you can get pro discounted pricing on larger orders as well.

Here's an article with additional FAQs on cost segregation studies.https://www.biggerpockets.com/forums/51/topics/1113749-cost-segregation-faq

I'll do some additional digging in the comps with that lens in mind and report back.