If you aren't sure if it is a legal suite, find out if permits were pulled (or needed) when the kitchen was put in.

Unless you have something explicit in writing that they permit you to move forward, I'd hold off.Consult with counsel.

Aside from zoning issues, permits, and city/county requirements, which are highly variable, I'd like to get an idea of how many units/buildings and how to lay it out for most efficient use of space for those 2 acres.

Well, its likely in there somewhere. 5G is going up and adding equipment which warrants an increase in rent if the lease doesn't permit expansion.

Building permits, a leading indicator of future construction activity, were up by 1.5% to 1.80 million units.Rent costs rising over the past few years could finally be hitting the consumer's wallet in that they are becoming weaker and unable to afford higher rents.Also, looking at the housing starts data, new supply may be entering the market finally, causing prices to drop as consumers have more options. 

If something like government placing Covid eviction moratorium that permits the tenants to not pay rent for a couple years without a means to evict happens, that can result in a purchase underperforming my underwriting. 

Did work get done in the past without a permit that they discovered?

Lenders are not permitted to disclose loan terms conditions or even borrowers names until the loan is in foreclosure.

"It is not legal to divide an existing dwelling unit into separated living spaces, thereby creating new dwelling units, without first obtaining DOB work permits,"  That would be an illegal conversion and can result in violations and other enforcement actions.

Yes, you can sell it.Sometimes Peoria will grandfather a duplex and refer to it as a "legal nonconforming" single family zoned property with duplex as permitted use.If this is the case the new owner will be able to legally and officially use it as a duplex.I have also heard of people finding an architect to declare that the house was originally built as a duplex, which would help you get it rezoned as multi-family and duplex as permitted use.PM me for more info.