Also wondering if anyone knows where I could find vacancy data etc, as I think low vacancy rate areas would make renting out easier?

I'm not a data scientist or statistician. 2. 

It should be similar to looking at "sold" data in Zillow.

As the property increases in value, I use financial strategies to Refinance the property and pull out my original investment.

But it is becoming way too tedious and time consuming to input all that data, as there always are so many individual expenses, even for just 6 units. 

Texas tax laws dictate that an appraisal district in each county, administered by a chief appraiser, is responsible for appraising property values each year.For a the appraisal of a taxable property, property tax is determined as a percentage of your home’s value, so the more your home increases in value, the higher your property tax bill will increase.

I normally access most of this sort of data from the U.S.

Show data?

@Shawn McCoy the standard deviation on R/E IRR is much tighter than PE because the underlying asset (real property) is more stable in value than a business enterprise undergoing the PE value add.

Double-check that they have included insurance, vacancy and maintenance taxes, etc. whatever assumptions the company makes in their pro formas, you need to get the data that backs those up - what are they based on?