"Lion's Run" is the US title for "The Bear's Tears". It seems an odd change of title as an essential plot element of the story is a KGB file codenamed Teardrop.
"Wildcat" is the US title for "All the Grey Cats". The US edition is missing the epilogue where Aubrey visits Ros to ask about Hyde. Indeed all other references to Hyde thoughout the book are deleted.
"David Grant" was a pseudonym used by Craig Thomas for two of his early novels: "Moscow 5000"  and "Emerald Decision" . I assume the name was used because he already had "Snow Falcon" out in 1979.
While "Emerald Decision" was revised and reprinted in 1987, "Moscow 5000" never returned to print since the 1980 paperback came out.
It is set during the Moscow Olympic Games of 1980. The "5000" refers to the 5000 meters race. The main plot points deal with a terrorist plot to cause a nasty explosion during the Games and also a defection.
No. It appeared in hardback in 1983, the year after the movie of Firefox was released. from that point on the UK paperbacks of both Firefox novels had covers depicting the movie MiG-31, creating the impression that both books were adapted.
In the USA during the 1980s all the Bantam paperbacks of Craig's novels were given covers that looked a lot like the Firefox movie poster, thus cashing in on the movie link.
"Firefox Down" was also dedicated to Clint Eastwood, and the description of the plane changed from silver-coloured to black.
I don't think that official drawings were ever produced. There are some fan drawings out there. If you want something professional you really should check out Kurt's Firefox site at www.thinkinrussian.com.
Comet Minitures at one point were selling a model for £50. The model was made by Planet X and was a 1:72 scale model made from GRP plastic. They have a website: www.cometminiatures.co.uk
William produced a 1:144 scale model. You can contact him at WbNemo1@aol.com if interested.
To date the USAF pilot has appeared in: Firefox (1977), Firefox Down (1983), Winter Hawk (1987) and A Different War (1997).
A Different War (1997) and Slipping into Shadow (1998).
For some reason they were not published in the USA. This might have had something to do with the change of publisher in the UK. Up until A Wild Justice most of his books were published by HarperCollins in the UK (who also published his books in the USA in the 1990s). His last two books were printed by Little, Brown/Warner in the UK and these are the two books missing in the States. Strangely enough Warner is an American publisher.
Sadly all his books are currently out of print.
I don't know for sure but I suspect ill health was a factor. But he remains my favourite author by a large margin.