Around 1880. According to a couple of different sources, the first sucessful commercial model appeard in 1883.
The actions operation.
0-60 usd
A single shot pistol, a Derringer and even a revolver are technically NOT considered semiautomatic. To be semiautomatic, the weapon would need to use the energy from a previous round to cycle the action. Revolvers use the muscle energy of the shooter's finger to revolved the chamber.
50-100 USD
shotgun, rifle and pistol.
Yes, Coonan is one.
Check the receiver and barrel
The Colt M1911, a semiautomatic pistol invented by John Browning, was first made in 1910, and subsequently adopted into service with the United States Army in 1911.
What model?
Depending on EXACTLY what you have; 100-1000 USD
50-1000 or more depending on the specifics.
Probably not. However some pistols can be fitted with an aftermarketlaser sight.