If you look outside, you are much less likely to get motion sickness vs, for example, looking down at your phone. I get to try it every time I go to a theme park, on a fast rotating ride, if I look inside, I get dizzy and sick, but looking outside makes you resilient.
Yes. Also the driver can anticipate the various accelerations more accurately than the passengers since he is causing them.
As a passenger I find I can read in reasonable comfort if I can look up and out of the vehicle at each acceleration i.e. at turns, when stopping/starting.
