Besides the up front cost of the offered purchase price, title insurance, the tax bill, and annual property taxes, what other potentials costs should I be aware of (also mention any negatives to be aware of).Thanks in advance.

You have to do an analysis of what the cash flow is taking into account - mortgage loan and rate, insurance, taxes (High in some parts of Texas) Vacancy, repairs, cost of processing applications, showing, writing up leases or paying property management to do it.   

The lessons that I learned the most, were to be firm with your rules, and definitely follow tenant screening, and don't take crap from contractors.

@Kai Van LeuvenIt’s sounds like you’ve gotten all the low hanging fruit, another couple things that come to mind Is reducing boring expenses that people typically dont shop or spend alot of time addressing;-taxes ( I don’t know how tuned in the city is to your remodel but you want to spend a little effort ensuring you don’t get hit with a property tax increase )- I’m not sure the type of tenants your looking to attract but a playground might go a long ways to adding value-Insurance ( anything you cad do to reduce your insurance?

You have no expense for insurance, repairs, vacancy, or HOA this is a townhome so I am going to assume it has HOA. 

He is one of the buy for cash guys . trying to wholesale . and he suppose to insure the title .

Sure, you can spend days drawing lines that connect boxes on some Donald Trump level real estate empire org chart in an effort to gain anonymity and avoid liability, but, at the end of the day, what protects business owners is adequate insurance and acting intelligently."

@Raj G.First thing, did you get a copy of the insurance binder that shows you as "loss payee"?

The next day I have the docs notarized and arrange title/property insurance, then we meet and exchange loan docs/insurance/checks and pay for the auction.

Often these management firms have interested applicants from other properties recently listed.