The name of the rifle is Hawken, after the original makers, Samuel & Jacob Hawken of St. Louis mo. The name became used by other companies making a rifle that was large bore (.50 or larger) with a half stock, and set triggers. Many companies make, or have made, a Hawken style rifle. However, the "in line" muzzle loader rifles have reduced interest in traditional side lock rifles. You may want to check on line gun auctions, such as auctionarms.com, or gunbroker.com for examples. MY Hawken is a Thompson/Center "Renegade" .50 cal- and it is a great shooting rifle.
Check the on line auctions.
its a pretty gun that only blonde would use
Can range from 100-1000 USD
It is possible
Contact the maker or a gunsmith.
none that i know of
It should be a #11 cap.
If you are referring to a "SET Trigger" on a rifle. The Set Trigger releases all the normal mechanisms in the action but does not release the hammer on the rifle, but it sets up the firing trigger to act like a "Hair Trigger" just barley touch the firing trigger and the rifle goes off. It's used in hunting. It is common on black powder "Hawkins Rifles."
Kentucky rifle, Hawkins, Sharps, Dragoon, Musket To name a few.
A few hundred to museum priceless depending on specifics
50-275 usd
Ivestarms ??