There have been many, many comics with the X-men in them as you mention. X-men, Alpha Flight, New Mutants, and X-Factor all feature multiple mutants. Spin-offs featuring one or two characters include Wolverine, Dazzler, and Cable. Then there were many issues where some or all of the X-men made guest appearances in other titles, such as the old X-men in Fantastic Four 28, Captain America 172-175, Angel in Tales of Suspense 49 (with cameos by the other X-men), Avengers 53, the intro of Wolverine in Incredible Hulk 180-182, new X-men in Marvel Team-Up 53, Annual 1, New Mutants in Annual 6.
This list could go on and on I think. And that's not even counting the many appearances of mutant villains of the X-men like Magneto who fought non-mutant superheroes. Or how about the Scarlet Witch and Quicksilver, mutants both who appeared as regulars for many issues of the Avengers?
Right now the Surfer could not be any hotter due to his inclusion into the new, Fantastic Four movie. History shows that a character that makes it's way into the mainstream, a la movies or TV has an instant surge in popularity which translates into a run on buying their books which usually translate into big, inflated dollars for collectors and vendors. If I understand your question, you want to know if these books are worth anything, right?
Well, the obvious answer is, yes! Yes! And Yes! I suspect you're really wanting to know: "What are they worth? How can I sell them? The problem with selling/appraising an item that fluctuates in value based on the wants of collectors is that it's only worth what someone else is willing to pay for it. To get the flavors of what your book is worth you should check out some price guides which approximate their values based on a criteria of how your particular book is selling in several parts of the country factored together with the number of books available for sale, etc."
Wizard and Overstreet both publish guides that will help you with this. You can find these guides at a local Barnes and Noble. You can also check out a more "real world" marketplace by plugging your book into some kind of online auction or another auction sites and see what it's selling for or if books like yours have sold. Next, you're going to want to discover exactly what condition your books are in because the quality of the book is the most important factor in determining what it's worth. For this you can self grade or get a comic book store guy to do it but be ready for a lot of slings and arrows from people that will tell you that your grading skills stink and that your Near Mint is more like a Very Fine, if you're lucky.
The industry has taken a turn towards legitimizing its "grading with the establishment of professional certification organizations that will professionally certify your book for a fee. The book is graded by experts, sealed and authenticated. I like this because it provides an unbiased 3rd party evaluation and comes with the pedigree and paperwork that collectors can trust when buying a book. The service is not new but it isn't necessarily Lloyd's of London so it will take a while to eventually become the industry standard but at some point it will. I liken it to the idea of getting a complete history of a used car faxed to you from a State Agency as opposed to just taking the word of the seller.
CGC and PGX are two such book certification companies but I think you could probably find a professional appraiser in any city. Again, you want the appraiser to be an unbiased 3rd party who is making a living at this and is willing to provide certification and pedigree. See some examples of his previous work. There are several factors that have a direct influence on the value of a book. Some of the ones I use are: condition, print run, availability, scarcity, origin issue, major storyline, new character, new developments, etc.
The Silver Surfer is hot, hot, hot right now and it's probably the perfect time to sell so it's up to you. As far as the cover being off the #1 issue you can have it repaired by a restoration company but it must be identified as repaired when listing the book for sale or having it appraised. A lot of people out there would love to get there hands on this kind of comic book make sure you keep a very close on the price range when you have it up for sale.