is it 100k-150k rehab project and so on and so on...for example i know if i have to replace the whole plumbing the whole cost would be $15k-$20k, so it's known factor before I even started looking at the house.

It's a beautiful home (in Rancho Del Oro) and hasn't been vacant a day, but we've had several issues through the years with the plumbing.

Even though they are renovated, they have to be pretty old in Richardson, maybe 70s vintage, so I would want to know who rehabbed them and what did they actually do....like new electrical and plumbing...any foundation work?

This may involve adding ductwork, installing a separate HVAC unit, or using portable heating and cooling units.Electrical: Another important consideration is the electrical and plumbing systems.

Providing more information about work completed probably helps most sellers because absent some sort of documentation on upgrades, or major work or accessibility to infrastructure, I'm going to assume that if it's an old building it has old plumbing and old electrical and submit an offer (or not) accordingly.

I don't think it is a good idea any more than you should also get your insurance broker's license, your title insurance license, your contractors license, roofer's license, and while you're at it HVAC certification, Electrical and Plumbing Master licenses.Some people do both, but I think for the majority of people there is enough to keep up with on either business that if you try to do both you do neither the justice it deserves.   

The rental we lived in were white boxes with a roof and working plumbing.

the plumbing?

Year built3. year of updates (roof, plumbing, heating, electric)4.

I do have good folks for plumbing, flooring, landscape, fencing and paint.