You use a shotgun style load in a pistol? Enquiring mind ... ;-)
I looked it up - perfectly safe for your handgun.
You may have to clean the barrel more often due to lead buildup if you put a lot of shotshells through it.
Sure, just make sure it is not a ported pistol. Speer makes these loadings just for that purpose. They usually come in 22, 38, 44, and 45 caliber. You can even order just the blue plastic casings and load your favorite sized shot. I just ordered a bunch of 44 caliber for a 44 magnum and will load #9 shot for snakes.