Revolvers are not intended to be disassembled by the user for regular maintenance and cleaning. Would strongly recommend you find a qualified pistolsmith if you need work done. Spray gun cleaner can clean internal lockwork without taking it apart.
The Colt Trooper MK III .357 with serial number J11918 was manufactured in 1975. Colt's production of the Trooper MK III series began in 1969 and continued until 1983, with serial numbers indicating the year of production.
about 1973
100-500 USD
Colt data at Proofhouse.com
No serial number provided.
Around 1973.
1958
Can't be answered without the serial number.
Impossible to answer without the serial number.
Between 1971 & 1972
-5-500 USD or so
It will be marked on the weapon.