Determine what type of tenant you are looking for.
Evaulate the area.
Look for other duplexes on the market or zillow as a resource.
Ask your realtor or property manager.
Reflecting on my past duplex transactions, the exterior is priority. Look at the roof, exterior paint work, and rotten wood and other costly items that needs to be address by you or current ower. Your insurance provider will be looking for issues via 3rd party evalutor or in person after the transaction. Insurance providers will give you some time to complete. Some what it done asap and other 6 months. Use exterior defects to negatiate prior to closing.
Yes, Paint. flooring is optional. If its trash, then yes. Applicances would next to evaulate.
Also, look at what that city's regulations are regarding rental properties. Some officials are pretty strict. They may also have to inspect (inside and out) the asset to make sure its up to code. Another costly process if your not aware.
Get a home inspector to be your advocate to assess the asset.
55k a door is pretty good. At this price point, I'm not looking at ARV. I'm looking how much cash in going into my pocket. I will hold long on this asset, if I was in your position.
Rent to price ratio
Hope this helps a little.