I'm in negotiation on a duplex which was converted from a 2 bed 1 bath each unit to 4 bed 1 bath so total the duplex has 8 bedrooms and 2 baths (1820 sq ft). 

Eventually, you'll get good enough to keep a "pulse" on what the rents are just by looking at where a house is and how many beds, baths, and schools. 

Also, I had crappy pictures for the rooms, so I replaced the light bulbs with bright white 800 lumens flood lights and staged the rooms a little bit and took new, better pics and that seemed to help boost interest enough to get more people to come out to the open house which eventually lead to me getting the two new tenants in place.    

You'll eventually get there. 

My eventual goal would be to Airbnb the house.

General maintenance will be grandfathered in.And eventually when the other lot goes up for sale, you will be able to buy it easier than other buyers who may have loan issues  since you will not have concerns about the lot issues.  

You will eventually meet someone in your area that you click with that will help guide you. 

Take that number and times it by the sqft of the house you are buying to determine your eventual sale price.

Keep trying, and you’ll succeed eventually. 

I understand location is everything, and will be looking at properties in areas where appreciation values are constantly rising (3% per year).The idea is to rent these out at approximately $1400 per month (each), and eventually sell these properties within three to five years when I'll be able to gain between 9% and 15% profits from each property.