The 380 and 9mm are two different cartridges, and you should never try to fire anything out of any gun other than what it is designed to shoot.
No. Some .40/.357 Sig pistols can be converted to fire 9mm simply by dropping in a 9mm barrel and using the 9mm magazines, though. Not sure about the Glock.
DO NOT ATTEMPT THIS!!. Never fire ammunition in a weapon that it is not chambered for.
Yes, you can fire a .357 Sig round (not a .357 Magnum) in it, but you must first change out the .40 barrel for the .357 barrel.
No. The mags for the 9mm are different than the mags for a .40 S&W
Sig
No.
The .357 Sig is a 9mm projectile, loaded into a necked down .40 S&W casing.
No. .357 Sig and 9mm are two completely different calibers and not interchageable.
Follow the instructions provided by SIG
Yes
She usually uses the Sig P229 but in some occasions is carrying the P228 or P239
No, 9mm