You will have to define what you mean by "best". Is your primary objective recoil reduction, blast reduction, or a combination?
You will have to shoot different brands to find out which is "best" for you.
2860 fps
100-800 or so
Contact Ruger customer service through the Ruger website. Soem parts will require the rifle be returned to the factory for fitting.
100-1000 depending on specifics
Depends on muzzle velocity, projectile weight and distance.
100-1000 USD depending on EXACTLY what you have, its condition, box, papers, accessories.
Manufactured in 1987. For specific month, you would need to contact Ruger. For another question about it to be answered, you would need to give a specific question.
Depends on bullet weight, muzzle velocity and barrel length.
WSM = Winchester Short Magnum. A variety of WSM cartridges exist, i.e., 270 WSM, 300 WSM, 338 WSM BOSS = Ballistic Optimizing Shooting System. It is a a 3.5-inch long combination muzzle brake/weight. It threads onto the end of your barrel. By changing its position along the threaded muzzle, you change the length of the barrel and subsequent vibration/harmonics.
We can't tell without the serial number- but if you go to the Ruger website, under Customer Service, you can see the year of manufacture for serial numbers. You will need the spefic model of your rifle.
Long action. .308 and shorter- short action. 30-06 and longer, long action.