The long Built up

Yep, the French asked far too much in all their tank designs from the commander. Put that aside though and the Somua had a better AT gun in the 47mm, better armor, and better overall performance vs. the 35(t). It's not widely known/acknowledged just how thin skinned most of the German armor was at the time of the French campaign and a lot of hard lessons were learned which is why you see all of the in-production designs getting up-armored between June 1940 and the subsequent campaigns in 1941.

Actually the Somua had a 47mm and the Pz 35 a 37mm gun. I'd say the Somua wins that. The problem in the Somua, was the commander was also the gunner and was performing too many functions. 

The Somua 35 was more heavily armored than the Pz 35(t) and arguably, one of the best medium tanks extant in 1940.  Probably mechanically more reliable than the mediocre Pz 35(t) as well.  Their armament was similar.  The S35 wins in this matchup

The OT-26 would still have been in service in the '41 invasion.  It would have been there to face the German onslaught.

The M7 HMC did have provision to carry 105mm rounds capable of AT work.  Definitely not what it was designed for but it retained this emergency capability.

Can't help you with the first two, but the M7 Priest was mobile artillery, mounting a 105mm howitzer and is unlikely to have engaged tanks directly. It was not designed to do so.