The image is of a BT-SV, or a BT-7 with sloped armour.

This little guy: 
[img]http://wiki.gcdn.co/images/thumb/4/4c/BTSV_1.jpg/314px-BTSV_1.jpg[/img]

I'm not making them as capable as as that though, generally the armour will be thinner and rely on its sloping to resist most rounds and the speed will be around 60 Km/h.  Similarly I'll be going for a 37mm gun on them rather than the 45mm they had in reality.  Mainly I just like the look of it, and it won't be too related to it's real life counterpart.

As for the other tanks I'm still working out details to be honest.