Sometime between 1835 and today. Colt made his first handgun in 1835, and they are still in production. If you can be more specific, we may be more help.
1873
The repeating hand gun
You will have to call Colt to find out.
100-10000 or more depending on specifics
Around 1961
Can't answer without knowing if it is a hand gun or long gun and a detailed description of all markings and features.
Around 1916
You will have to call Colt.
You will need the model and type of gun- and check with Colt customer service.
Take your pick. Various Colt serial numbers and dates.cut & paste http://www.proofhouse.com/colt/index.html
colt
what is the value of a 1919 colt automatic hand gun