Age, pumping schedule and possible break down and replacement are all issues. 

The good news is, all of that is in the past.

It seems like a great way to break into investing if you can do it right.As far as purchasing a single family house or condo, I guess a lot of it comes down to the rent to value ratio in the area you're looking.

Selling  closing costs.I use as rule of thumb  10% of gross when I do a quick look at properties but to break it down6900    6% commish1000    tax s for 6 months property taxs as we know in texas are sky high.750      builders risk policy500     utilities  got to have those to work on the house1200    sellers closing costs  ( not sure if you included buyers closing cost in your pp)500      misc10,800     10% of gross would be 11,500 so pretty close there.89,270      PP100,120   Sale price of 115,000   equals   profit of  14,800.00  which equals a 40% APR for time held...

one last try...Can anyone help me break these numbers down?

You'd have to be more specific, and break it down for us.  

I once had a water main break on New Year's Eve on a 128 unit apartment. 

I am not sure about putting that kind of information on here, as well not allowed to post contact information, I would like to make contact with you, Ming, without breaking the rulessuggestions there would be nice as wellthank you

Whoa whoa whoa pump your breaks everyone.

I am not excited about the fat 39.6% tax bill I am creating for myself (good news bad news about having a good day job).