No, Izhevsk did not produce AVT's. Wide trigger quard is not equal to AVT trigger guard. It's just production simplification.
Can you post photo of this Izhevsk marked wide trigger guard? I read about them, but currently don't saw at least one, they are rare
No, this is another book. It will be much more interesting for collectors. Currently it is not published
But in book that you mention, there is a production data for Izhevsk SVT's, since beginning of mass production in August, 1940, untill the end in October, 1941.
Besides, there mentioned document, according to which production of SVT's in Izhevsk was stopped - order #383 cc from 20.08.1941 by Ustinov D.F.
And for Tula there is production data for July 1940-December 1940, and July,August, September 1941
You are correct, SVT thick stock exist, I missed it in my post. Not sure when their production was started, but it was definetely stopped after beginning of AVT production. Even late Sniper SVT's were issued in AVT stocks - there was no sence to produce special stocks for them.