The Pak 36 is weak yes its simply to hold off early armour. Its ablity does allow it to efficiently pierce the armour of a T-34 at close-medium range but not an IS-2's which hopefully by the time it arrives you've already built a Marder II etc.
One of the few units i've got some doubts about a usage in your concept. I mean this pak is extremly weak.. a compareable weapon i mean pretty much the same is on the AT halftrack and its doing only 30 damage. Thats nothing at all. Even with a AP shell ability which would duplicate the penetration and maybe give some more damage this wouldnt be that usefull still.
Jagd[tiger] is a buildable replacement for the Kettenkrad... It can cloak and cap points.
OSTHEER IS DONE WHEN IT'S DONE!
Yes, but in later game stages you have absolutely useless weapon. It should have some advantages, but as far I see there is only camouflage and "One strong shot -then die" ability. For instance Wehr PaK is quite powerful even against heavy armour, and you have one strong at gun and one so-so at gunt. So give it some advantage against other units types because it lacks of at firepower.