I think the "anti-matter" part of the cannon concept has been removed, just leaving them as "cannons". Not that we're specifying the exact details; you can imagine them as any kind of cannon you like.
Haha, true. The "no sound in space" thing is somewhat of a misconception. (I was hoping someone would call me out on that.
) In truth, exactly how "sound" (vibrations in matter) is really handled in space/a vacuum isn't important for the game's mechanics. For the sake of gameplay and the general comfort/familiarity of players, it's probably best that sound is just handled as we are used to. (Through air and other volumes of matter.)
While I can't make any promises and, as I said, the lighting system doesn't lean toward dynamic lighting, I agree that a flashlight would be nice. Hopefully it'll be possible/added in the future.
Also, that thing attached to your wrist is known as a Fabricator.
It is wired into your nervous system and manages all astronaut-based manipulation and storage of blocks, as well as a myriad of other important functions for any StarMade astronaut.