How do I script this stuff on vehicles?

Hi, I'm new to scripting and I'm planning to make my first place where players drive armed cars and shoot each other. I have some questions on doing advanced stuff.

• How do I add weapons on the vehicles that fire when a certain button is pressed?

• How do I give the vehicles a health meter that depletes when weapons hit them?

• How do I add powerups? I.e when your vehicle touchs a powerup crate, it grants an one-time weapon.