It would be even better if we could get it zoned to rent out the house as a 3/2 and separately rent out the ADU as a 1/1.If anyone that sees this has done something like this in Columbus, we would love to get any info on how the process went, how much did the permits and inspections cost, etc.Also, if anyone knows whether or not we could even rent out an ADU through sec-8 that would also be helpful, as we will definitely consider using sec-8 to rent out the property if it can get us higher rents.We are going to be contacting the city's zoning dept right away to verify with them that this would even be allowed at this address, and to try and get a rough estimate of how much permits etc will cost us.

Verify all information and don't be pressured into doing a deal with them.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Market Selection Criteria: To choose the right market, consider factors such as:Economic Growth: Look for markets with strong job growth, a diverse economy, and increasing population.Rental Demand: Identify areas with high demand for rentals, which can be indicated by low vacancy rates and high rent-to-price ratios.Affordability: Ensure the market offers properties within your budget that also meet your cash flow and appreciation goals.Property Management Quality: Verify that there are reliable property management companies in the area to handle day-to-day operations, especially if you are investing from a distance.Comparative Market Analysis: Perform a comparative market analysis to compare potential markets.

Most competitive lenders will want to verify the above.

And is there any way to verify it has actually been done properly if and when we get there?

Verify breed and specific dog.

I guess I am wondering what else I can do to verify that the lending firm is solid? 

Verifying last 2 years of rental history very important!

If the successful bidder assigns his interest in any real property purchased at the Delinquent Tax Sale before the end of the redemption period, the grantee from the successful bidder shall furnish the Tax Collector with a conveyance, witnessed and notarized, a copy of the bid assignment form may be obtained from the Tax Collector's Office.Bidder checks (for the bid amount plus interest) will be mailed to the successful bidder, or their grantee, once a property has been redeemed and funds have been verified by the Tax Collector and pay periods have been determined.