My main concern is whether it's hard to meet their criteria for properties and secure funding.

As mentioned the main downside to using a SDIRA to purchase properties is you get no tax benefit upside (depreciation) and have to pay taxes on UDFI.

There are other communities that would have better opportunities to cash flow.Although there is no guarantee of future income on any STR, I believe that 2025/2026 we will see a good increase in travel, mainly due to EPIC opening and the overall attitude of 'the people' coming off of the election.

Without getting into the weeds on the point of view arguments and everything between you and the seller, the main take away here is that the seller doesn't want to sign your mutual release.

To make the job flow easier, but also (mainly) to protect myself if a customer changed their mind later ( which was common).

If you're refinancing to a business purpose loan that's totally fine, but chances are good you'll need a lease in place for the unit you were occupying so the lender feels confident that it's strictly going to be used as an investment property.

Mainly how or if you offer them at your STR.

The fact its in a landbank tells me that it was taken back for some reason, which tells me its likely not a high commercial demand for development, but I could be wrong.If it is "on the main drag" in this town then I'd think doing a new build home to do a targeted and intentional air bnb would be the best bet. 

My main focus is Class B and maybe some C+ properties around NE Columbus, as well as outside 270 from the North to the east side.

One main regulation I find in Ontario Residencial Tenancy Act section 134 (3) states you cannot make a profit in subletting.