just bought the game, now i have a few questions

[Phoenix-D]

You always get half value back for ship upgrades.

Enemies are marked with red triangles on your smaller radar map (press R). They're also the ones that will fire on you. In the stock game, enemies will always be enemeies, but you can make friends attack you temporarly by shooting them. They're dot will turn red and they'll attack.

Apart from commodities, in the stock game things will always buy sell for the same price IF you're at the same race's planet.