I would recommend talking with your real estate agent for contractor recommendations. A good agent will have a list and should be able to provide you one or more recommendations for what ever work you need to have done.

Get an engineer to perform inspections for you, especially if you are thinking about removing walls and re-routing plumbing and electrical. Those walls may be bearing walls and could weaken the structure of your house. You should be getting inspections anyway. It is money well spent, even if you do not buy the house.

Here is a tip. You may be able to get a rider on your insurance to cover the replacement of the waste line from the house to the street. A couple of $ a month can save you $10K down the road.