Like stated the accuracy is strictly military standard.You're not gonna win any matches with it.P38 and the slightly changed P1 use most of the same parts,slight change to the firing pin,and there are part kits currently available.
Holsters are available as long as you go with a military issue,never really has taken off for CCW so your best bet would be a custom holster.Magazines are abundant,so go ahead and enjoy,like my Luger its fun to shoot.