As to your first question.
NATO 124gr 9mm ammo is rated at 1200fps and 396 ft/lbs. It is HOT ammo. I would not suggest use of a steady diet of +P ammo for any firearm. It will cause excessive wear On the gun over time. It will also depend on how much you shoot. I might fire 200 rounds a year. No worries there. I carry +P ammo in my Carry gun (Speer Gold Dot 124gr) Or HST 124gr reg vel. but practice with standard velocity ammo. JMO

As to your second question.
jsbethel has a good answer. You can always call S&W and ask them. Also ask about the hardness of the frame, steel vs aluminum.
Enjoy your 39 series auto!

Be SAFE and Shoot Often!