1) When you say configuration of lot - can you clarify what configurations do you consider advantageous?

Ratios for screening deals, bedroom/bathroom configurations, rental rates, local norms for tenant-paid utilities, desirable areas, etc? 

Around here, shotgun refers the room configuration (one room that leads to another, no hallways).  

Sometimes these types of configurations don't bring as much value as you might think.

Rents in the area for this size and bed/bath configuration are going around $1300 to $1450 per month. 

.* What configuration rents best: two bedroom, three bedroom, etc.* What is the best location for such properties: North of the river, east of 35th St, within two blocks of mass transit routes, etc.* Best rental price range: If the median income for the people who rent properties is $4,000/Mo., trying to rent a property for $2,000/Mo. is not going to work.

If the area passes all the above (there are more criteria but these are the main ones) then you are ready to consider what type, configuration, location and rent range do best in the area you are considering.

If you configure your code in a smart way then this should be an easy swap in the future.

(light in room, configuration, style, etc.) 

Configuration of the unit 4.