Re: Steel Panthers-Individual Soldiers
 

Could you bag a tank with a side shot, maybe from a panzerfaust or M72 LAW?

There's already marksmen in the sniper slot, sometimes with assault rifles, rather than a sniper rifle.

Re: Steel Panthers-Individual Soldiers
 

Yes, there are marksmen with non-sniper rifles, though usually with bolt action rifles for SPWW2 (though there are some with assault rifles in MBT).

Generally bolt actions were considered more accurate than semi-automatics, and thus were retained in limited use after the introduction of the latter - for example when US Army adopted M1 Garand as the main armament for WWII, the older M1903 Springfield was still retained as a weapon for sharpshooters, and every infantry platoon was officially assigned one for use by a platoon marksman.

That said, in late WWII Germans also experimented with assigning semi-automatics to snipers.