I don't have any advise about puppies that young, except that anything you are doing for them seems way better than what they were getting. Good on you for taking them in!
A Vet's office should be able to tell you what to mix for food and what to do about the ticks.
I do know you'll need to work extra hard to keep them warm since they don't have momma until they can self regulate their body temperature. Maybe a heating blanket in their welping box?
Jack- GSD/Husky Gotcha 7/24/2005- Rainbow Bridge 4/7/2012
Ollie-GSD DOB 4/15/2013