No problem. I use a combination of a realtor & averaging a few comparables of homes sold within the last year on realtor.com & zillow.com. No one site is extremely accurate but if you take averages, you usually get a pretty good figure.
As far as driving for dollars apps I haven't implemented any yet but I constantly hear landglide and dealmachine can really lighten your load.
I really lucked up when it comes to contractors. 1 of my partners is an architect and I have an uncle and a childhood friend that are professional contractors. A suggestion I've heard is to actually stop and talk to contractors you may see out working on properties.
I'll have to check out that Driving for Dollars Apps! Ive found a few on my own, but always looking to improve and try something new.