Reporting Sale of Second Home in Turbotax questions

So I was going thru the 8949 tax return that turbotax created and I have a few questions:

 

The basis is your original cost of the property plus any improvements if you purchased the home?

 

So if I add a radon system, water heater and fence is that considered an improvement? 

 

If so does the improvement need to occur from the date I owned the property until the date I sold the property? 

 

I notice Turbotax puts it under adjustment of basis rather than add it to cost? Which is more accurate?