Yes, all of our products are certified and will have the appropriate markings on the products.
USB Power Delivery (PD) is a universal charging standard that enables compatible devices to charge at much higher power than normal. The technology supports bi-directional charging and data transfer from both host and peripheral. Fast charge your Pixel 3 or iPhone, and then use the same charger to power your MacBook. Get more detailed information from this blog post.
Yes, they can stay plugged in when not in use. However even if the car is not running, the charger will continue to use a small amount of battery power, even if there is no device plugged in. This could affect the battery of your car if it is not driven for long periods of time.