Hi! There are now Controls Tips in the game in the latest update, making it super intuitive. :)
You can also see the Controls listed in the Options screen from the main menu.
If you're on Mouse & Keyboard, it's:
- "SPACEBAR" -> Jetpack
- "F" -> toggle Slow Motion
The gun doesn't need to be reloaded, it's fully automatic for both ammo types. Just keep an eye on your ammo counters (shown on the gun itself).
You cannot pick up the weapons that the enemies drop, although I could consider adding that in, so when you grab a weapon it gives you a bit more ammo. :)