-If your credit is too low, banks won't generally lend to you, so you'll want to figure this out and improve your credit if need be.

You mentioned capital improvements, would this be similar to an upgrade rather than fixing AC or replacing water heater etc?

Knowing where you want to go begins with knowing where you are, and with that in mind I reached out to a national bank just to see what kind of mortgage I could qualify for and how I would best improve my current situation in case I needed to use conventional financing.My credit score is mid-700s, about $15k in consumer debt (which is coming down).

I know there are several sources out there to obtain lists so who do you guys consider to be the most cost efficient? 

From a cost standpoint a 10 x 30 would be more efficient if you have the space. 

You're on an investing forum so have you put much energy into the investment side of things?

A few specific concerns would be the length of the lease, the credit strength of whoever signs it, the strength of the tenant's business, and any rehab or Tenant Improvements (TI) discussed in the lease. 

All need improvements ($5k-$10k/ unit) and rent can be increased substantially.

The main reason why homeowners opt not to pull a permit is because building improvement will increase property taxes.

What we have done: all new kitchen 6 years ago, all new bathrooms last year, new energy-efficient windows and sliding glass door, new drywall texturing, new base and case, created a 4th bedroom in the basement (cut a window and finished the room), new HVAC 4 years ago.