In all likelhood, one of the bolt action pistols in a rifle caliber, such as 6mm. That holds the accuracy record for a rifle, and would likely do so for a pistol.
The most accurate handgun is the CZ 75 SP-01 and it retails at around $600 - $700.
Either the SIG or S&W
A VERY good handgun- for most puposes. Durable, reliable, accurate, and powerful.
double (or, on some platforms, long double)
It depends on the model, but most handguns are meant for short to medium range conflict.
Depends on the firearm, what you are shooting, and where you are. With a rifle, firing from a supported position, such as a benchrest is the most accurate. In the field, the prone position is most accurate. However, that does not work well if you are in waist deep grass, or duck hunting with a shotgun. With a handgun, a two handed shooting stance is most accurate, and using a support makes that better.
Rifle, shotgun, or handgun? The 10 gauge shotgun at close range would be very high on the list, as would some of the buffalo rifle cartridges, such as the 45-110. The .45 Colt revolver was possibly the most powerful handgun of the day.
Handgun - 38 special Long gun - 12 gauge
Slightly over 11574 days, or about 31.7 years. The range would vary if you actually tried to measure it because most clocks don't stay very accurate for such a long period of time
A water pistol.
No
Handgun