Are the units currently occupied and tenants paying market value for rent? 

Qualified mortgages (VA, FHA, conventional etc.) get underwritten to Fannie/Freddie/Ginnie standards and get sold on the secondary market as securities.  

Hello,I am interested on thoughts about the current real estate market in Peoria and East Peoria.

I'd suggest asking your lender to mock up what it would cost to get your rate to 5% and then do a cost-benefit analysis to determine if that's the best use of your funds. 

If you ever decide to list those properties for sale on the open market, you know who to call.

The property features two 1,400 sq ft suites on the main level (one currently leased) and over 3,000 sq ft on the upper level, with 750 sq ft already occupied, 3 small office spaces (+/- 250 sq ft each), and a basement tenant with 1,400 sq ft of storage space.The building generates $6,000 in monthly gross income from its five tenants, but with full occupancy and market-rate rents, it has the potential to bring in $10,000+ per month.Given its historical significance, stunning architectural details, and location, I’m curious about your opinion: Would this property be more marketable for sale with or without the current tenants?

The macroeconomics is great - lots of population growth and job growth that's why the rental market is very strong.

If you want to network or ask specific questions about your local market, go to your local real estate forum and connect with investors from your area: https://www.biggerpockets.com/forums/86-local-real-estate-networking5.

You're in a market where property values could be very high 10+ years from now.

Work hand-in-hand with your broker and leasing agent to confirm what market rates are doing compared to what is being paid currently.