First of all, very sorry to hear of your father's passing. I'm sure this is a difficult time for you and your entire family.
As to your questions, we can certainly give you a place to start as you go through your father's collections. The first thing I'd recommend for your older, individual Case knives is that you take very clear and close-up photos of your knives, especially of the tang stamps.
As far as the sets are concerned, taking some good clear pictures of the entire set itself will help. Also, checking for recently sold items on eBay that are similar to yours will give you a good idea of what people are willing to pay.
You could also purchase a membership here and sell some of those items as well. At first, this kind of thing can be overwhelming, but if you start slow and gather necessary information first, it will get easer as you learn things.
Also, I wouldn't be too quick to sell those Case knives. You could very well change your mind in the future and wish you had kept them to pass down through the family. You might want to take a step back and consider this carefully. Once those knives are sold, they are gone forever.