VEVOR Rolling Pet Carrier Backpack with Removable Wheels for Under 18LBS, Large Soft Sided Wheeled Dog Carrier Cat Travel Carrier Airline Approved for Small Dogs and Medium Cats with Upgraded Wheels

I don't think so, it is quite stiff and wouldn't be comfortable.

Yes you could but the plastic base will have to be attached to the fabric body

This carrier is not waterproof.

Please kindly see the video in the below link for reference：https://send.now/7wcxpxigky6e

This is not a car bag, and there is no part designed to fix the car, but you can use the car seat belt to pass through the back trolley cover as a fixing mode

Yes, but you have to lie flat on its back.