Any insights or tips you can share about the Section 8 process, the Birmingham market, or challenges to expect?

I also have $102k in a money market account that currently earns about 4.5%.

Demand in the market was very high after COVID.

I would add Facebook Marketplace to your list for marketing.

From what I've seen in this area right now, it seems like you'd have a hard time paying market LTR rents and making a good spread. 

The fact that they share a wall doesn’t change the fact that they’re independent properties.2️⃣ Provide local market comps – If no duplex comps exist, that means the market isn’t valuing properties this way.

You could put it on the market (and you'll know what that second assumption is), and at the same time do whatever you can to get the tenants out (and know what the first assumption is).

Low down payment AND it cash flows also AND buyer has title.Maybe I am asking too much, but I don't think so.Perhaps you just market to homeowners.

Does anyone have experience with ADU's (accessory dwelling units) in any market, but particularly Cincinnati?

You'll have better luck analyzing a few properties a month from investors, wholesalers and realtors that can find you off market deals.