I have two questions regarding Tank Shock
1) If I use anther unit's ability (Man In Charge) to move a tank. Is it a valid move to move into a zone with enemy infantry and use the tank shock ability?
2) Can I move a tank onto a zone with my own infantry, risking sacrificing my units, in hope of missing, and allowing me to re-position then?
Two great questions!
1) Yes, I think this is reasonable; as it would be legal for a unit to occupy a grid with enemy units.
for 2) no, Tank Shock is defined in the rules as:
TANK SHOCK (X) - Units with this ability
may move into grids containing only enemy
Infantry units. The unit moving must otherwise
be able to enter that grid. All units in that grid
suffer a Flat Grid attack using X dice. Units not
eliminated by this attack are then moved into
an adjacent grid, chosen by the defender.
So, unless there are only enemy units in the grid, no.