Its my first game so thanks for the feedback! Particularly on the control, for me it is comfy to use shift with one hand, but that is just me! I should open the controls up more for different size hands and keyboards (gamepad is best xp for this one I think)
So you know where I'm coming from on the boost / shield. I am trying to make the boost feel as uncomfortably fast as possible and necessary to use without being completely impossible. Like nitrous in a car - no going back once you've fired it - and hold on tight! It doesn't shine through quite enough in this prototype version yet - but you'll want to finish fast as you can to score points. Basically hitting the target time means a lot, and if you go to slow you'll get overtaken. The shield activation time will be quickened so it requires you to press the button closer to impact, more as a last second block. Interesting to hear your take though, I personally only use the shield sparingly and found the boosting's unwieldiness to be so fun to warrant making a game out of it.
Cargo - You are definitely right, it doesn't have a damage cooldown so collision damage can damage it a bit too quickly. There is damage to cargo pods based on velocity but I think it is seeing the sheer/perpendicular friction force of the wall the same as impact force. Cargo pods will be made more plentiful too.
Turrets - totally right, they do break the RED = baddie rule and will get some red on them to define this.