Sidelock or Boxlock is mainly a personal aesthetic choice. If you want more area for engraving a sidelock provides that. The only real drawback to a true side lock is that it removes some of the strength of the stock right at its weakest point. I say true sidelock because there are some sidelocks that it is merely a plate that looks like a sidelock.

Extractors simply pull the cartridge up out of the chamber for you to physically grab and remove. The Ejectors expel the case from the chamber automatically usually tossing it a few feet from the gun.

BB
BB