I could say a lot but I'll just add a few points. When trying to determine what a property will be worth after it is rehabbed you can ignore listing prices. You want to focus on the sold price of similar properties in close proximity to the property you are considering. Second to get a feel for why one property lists for 25k and another for 70k go and look at them with your REA friend. Your RE agent should also be able to pull comps for you as well and you can take a look at the pics from when the properties where listed.
You will also want to be evaluating these properties from the proper perspective. Use the 70% formula to determine what you should be paying for a property.
MPP=(70%*ARV)-repairs
.70*70k-20k repairs=29K MPP (Maximum Purchase Price)
ARV= After Repair Value
There are tons of articles on here that cover rehabbing and flipping.
I strongly recommend J Scott's book The Book on Flipping Houses.
Wish you the Best