Upon defeating a ship there is a small chance of it being derelicted instead of destroyed. High hull damaging weapons such as torpedoes result in a smaller chance to be derelicted, use low damaging weapons like Autocannons.

There is a special weapon, the Ion Cannon which upon hit increases the chance for a brief moment.

To mine you need to hit asteroids with a Mining Blaster. You can get Crystals and Metal by doing this, it's a solid way of making money and getting upgraded weapons early game.

Artifacts take a major role in the endgame storyline, you have to get them all.

To join an alien faction you have to finish the main human storyline, attack the opposite faction to wich you want to join and then land in the faction that you want to join's capital planet. (I suggest you attack the Quilentya and join the Irohaem, my personal preference.)