To be a successful real estate agent and investor at a young age, you are going to have to really be knowledgeable on all aspects of real estate investing.  

One story v. one story, age, same subdivision or as close as can be, same schools and district, etc.

But at our age you're up several times during the night for those annoying toilet trips that makes the ensuite bathroom I added an absolute necessity.

The age of the house also doesn’t matter. 

Depending on the specific property, I'd expect higher construction costs due to the age of the properties.

A 3/1 may be 1200 sq ft depending on age for a price point in this range.  

There are several people that this is the case for in different areas of the country.My guess is my Lake house is a family vacation destination and more middle age people use VRBO when looking for a Vacation.

The home inspector should be able to tell you the age of the central A/C by looking at the serial numbers. 

We had to move into a bigger place to accommodate my aging mother, so now dealing with a big mortgage on the new house, 1/2 of small mortgage plus interest-only HELOC.

Kudos to you for thinking about this at age 20 instead of 30.If you want general advice for your situation you can find plenty of that on this website just by looking around, reading articles, and browsing forums.