Welcome to the forum.
My approach to assessing a collection has two basic data points:
1. Get a reference guide to you can determine a catalog value and know which are the gems of the collection, how to grade condition, etc. This can be a fun process to learn about a hobby a relative enjoyed.
This might be a good starting point (Scott is popular brand for stamp catalogues).
http://stamps.about.com/od/findings.../2009FDC.htm2. I then like to see what items are selling for in the real world.
ebay is a good reference for real market value in terms of how available are the items and at what prices they are selling. A quick look found nice empty albums of some of the covers you mentioned and here is a single:
http://cgi.ebay.com/1375-US-first-d...ft_W0QQitemZ370258824848QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item5635254e90
From there you are amred with some basic info to begin asking more detailed questions.
It's good to know the availability, value and a base knowledge of a collection. You can then determine next steps like selling, passing on to a family member interested in continuing the hobby (many hobbies start by beng passed down to another generation) or storing for potential future interest as a family keep sake.
Enjoy the process of exploring your Grandfather's collection. Some collections are valuable and others are just interesting and sources of adictive relaxation and education.
As already mentioned, FDC doesn't immediately generate hopes of significant cash rewards or even appreciation over what the original owner paid.