To move a physics object, you need to ApplyForce.
PhysicsSprite spr = cnvGame.PhysicsObjects["ball"];
spr.BodyObject.ApplyForce(new Vector2(xVel, yVel));
if you need your sprite to not rotate, you can use Fixed Rotation:
spr.BodyObject.FixedRotation = true;
Resizing (scaling) an object is a bit involved. I have done it for my app (demo here -
... but I have not yet created a function in Physics Helper for it.