Hi,
Correct, these are 70x101R cases for the type 92 batallion gun.
The band you describe is likely to be a darker brass base than the rest of the case is. One sees this commonly on IJA cases. Special loads were not indicated with colour bands on the case (instead the projectile would have had identifying colour bands).
As for the headstamps: all three of them have been made at the Osaka arsenal (crossed cannons). From left to right the dates are: September 1941, June 1941, and March 1941(?). The Kanji that indicates the year on the 3rd case is difficult to make out in the picture but I think it's the same as on the other two cases (the Kanji I refer to is featured directly to the right of the month indication (i.e. '3' on the respective case)). On your's it's composite, with the top half being a '+', which means '10'. Under that, a second Kanji is featured, which I think is the '6'. That number needs to be added to the 10, and in this case is then likely to come down to 16. To the right of that you can find the 'Sho' Kanji, that indicates that the dates are Showa era dates. Showa year 16 = 1941.
Cheers,
Olafo