Vickers six tonner - http://www.pendraken.co.uk/IW2-p6218/
Nice model, mate of mine has a couple for AVBCW. Very similar to the T-26 tbh
75mm IG - http://www.pendraken.co.uk/GR75b-p4359/
That's the Winter crew version, they do two more.
For the arty support, anything in the French/German sections in 75mm maybe? Not sure what theya ctually used specifically but suspect a variety of older pieces and German cast offs/captured bits and bobs.
The 45mm ATG you can use the Pak-36 from the German range or the 45mm copy in the Soviet range with Finnish/German crew - I would think they're pretty much identical in anything smaller than 1:1 scale