Yes
No dealer is going to specialize in those covers. There are not very valuable, the amount of gold involved is minimal. And dealer that works with covers will make you an offer.
If you were to approach a dealer, he might give you $50 for the book and all the covers.
The amount of gold is so small that it can't be measured. It is a layer an atom or two thick on aluminum. You can try to sell them on eBay or some other site, but there is little extra value to these replicas and stamp collectors typically do not want them in their collections.
This company produces a variety of products. Their first-day covers are real enough. I think they make gold or gold-plated replicas of certain stamps, which of course, are not real postage stamps. They offer some stamp and coin combinations that contain real US stamps and coins. I think they all sell at a discount of the secondary market.
There are many imitations and replicas created of the famous stamps.
Not cost effectively. It would cost you more to buy the covers and remove the gold than you could earn from the amount of gold in them. It is almost nothing, an atom thick layer on a piece of foil.
Barely, probably the face value of the stamp.
Not much. You can buy them for a dollar or two each on eBay. The gold value is negligible, it takes thousands of them to get a measurable amount of gold. You could probably get more gold processing sea water then from these things.
vary from 395 to 595 silver vale in 2013 approx 300 pounds sterling
They have almost no real gold, such a thin layer that it would take thousands of them to get a measurable amount.
The Dewey Decimal Classification for stamps is 769.54. This classification covers the topic of philately, which includes the study and collection of postage stamps.
First Day Covers are worth more than ordinary covers. Stamps bought on the first day themselves, without cancellations, cannot be identified as being issued on the first day. Leave them on the cover if you have them!