<human>: Can you condense the text into a few key points?

Hello, all :)!

I have a question dealing with kittens and road trips. 

I've recently adopted two little kittens (two 12 week old calico sisters), and I will be taking them with me on a trip (4 hours) to visit family. I was wondering what the proper procedure for long-distance traveling with them would be, what I should expect, and what supplies I should be taking with me.

I've heard suggestions like getting a big kennel for the back of the car instead of putting them in carriers. I've also heard that you should bring a litter box and stop periodically to let them go (I'm not so sure about this one) I've also heard some say you should bring food and water bowls with you while others say take away their food and water two hours before so they don't have to pee during the trip... 

I'm really not sure what to do to prepare them for this trip :(
<bot>: Tiny Kittehs on 4 Hour Road Trips. What's the best procedure to make sure they're comfortable and relaxed?