On the question of PA28 windows, a hammer, unless quite big, would be of limited use since they are not glass and the hammer is liable to bounce back and hit you.
However, the windows are only secured by flimsy aluminium clamping strips that are themselve secured to the airfame by few self-tappers which will be well worn in your typical several times re-glazed aircraft. Ultimately the strength of the window will depend on the type of mastic used and how well cured it is rather than any bolting in place.
A good shove would certainly push out the pilot's window due to the weakness of the DV opening. In an adreneline fuelled escape I doubt if any of the windows would resist a light kicking. It might be worth explaining that to PAX once they are belted in and can't run away.