As mentioned above, there's a decent chance that adding a muzzle brake will improve your gun's accuracy. On other hand, it may not. Worst case: Your previously accurate rifle may no longer shoot so well with a muzzle brake added.

Do muzzle brakes damage scopes?

Registered. Even with a muzzle break a good scope wont be damaged .

Do muzzle brakes affect recoil?

Muzzle brakes do reduce felt recoil. Those muzzle brakes not only direct pressure and gases up and to the sides but are also more effective at reducing felt recoil. Most companies that produce muzzle brakes will try to exaggerate how much their brakes will reduce recoil.