You need to define best for WHAT. There is no one "best".
A firearm
A shotgun is a firearm. A revolver is a firearm. A pistol is a firearm. A rifle is a firearm. If you want even more specific -- A Remington 1187 is a firearm (shotgun). A Smith and Wesson 686 is a firearm (revolver). A Sig Sauer P226 is a firearm (pistol). A Colt 6920 is a firearm (rifle).
There is no one "best" for everything. A Hammerli Olympic grade target pistol may be an excellent firearm for one specific competition, and fare poorly in another. A Ruger Mk III may be the leader in another competition, but is far to big for easy concealed carry as a defensive firearm. Depends on what you want the pistol to do.
A regular pistol is a firearm. It uses gunpowder to fire a bullet. An air pistol uses compressed air to fire a pellet with less velocity than a firearm.
A pistol is a single hand firearm with a short barrel.
Yes it is.
When someone utilizes a firearm (pistol, rifle or shotgun) to kill themselves.
A water pistol is not a FIREARM. You are in the wrong place.
The handgun was the only firearm he had with him.
A .357 firearm is typically a revolver or pistol that uses .357 caliber ammunition.
No. "Firearm" is defined basically as a small arms weapon, as a rifle or pistol, from which a projectile is fired by gunpowder. A slingshot is a weapon, but not a firearm.
Under MOST laws, no.