A few clarifications:
Side airbags are geat features, especially side curtains that cover all seating rows. Side airbags in newer vehicles are not considered a danger to children who are properly restrained in carseats or boosters. Also see:
http://www.car-safety.org/faq.html#Q61
The danger of a child sitting next to the driver is because of the frontal airbag and/or the dash. The risk of fatal injury for kids in the front seat is about 30% higher than those sitting in back, even without a frontal airbag, and over 40% if there is a frontal airbag.
I think your salesman is trying to confuse some related technologies.
First, there is FWD, which is standard front wheel drive found on most vehicles. The differential in most cars is such that if one of your front wheels spins during acceleration, all power goes to that wheel and you can be stuck even if the other wheel has traction.
All wheel drive and four wheel drive use improved mechanical differentials to send power to the rear wheels also, meaning that you now have to have one front AND one rear wheel spinning to get stuck. Some vehicles also have improved differentials between wheels such that any of the four wheels can get power even if all the others are spinning. These systems are great for getting through deep snow or very slick icy conditions.
Traction control can be added to any FWD, AWD or 4WD vehicle. This will use the antilock braking system to pulse the brakes on any spinning wheel. This can slow it down to regain traction and also cause more power to be sent to another wheel with traction. While traction control is generally not as good as a real set of locking or slip limiting mechanical differentials used in AWD or 4WD, it is better than FWD. This is probably what your salesman was talking about to try to confuse you.
Stability control is an added feature sometimes added in addition to traction control. It also uses the antilock braking system to pulse the brakes, but it does not do this for added traction during acceleration. Instead, it can sense wheel slip as you are losing control of your vehicle in a skid or spin. It will apply brakes to the appropriate wheel(s) and try to help you keep going straight to maintain control. Regardless of whether you have FWD, traction control, AWD or 4WD, stability control is an added bonus for safety.
I hope that answers some of your questions! I would prefer to have stability control on any vehicle, 4WD or not. On the other hand, a 4WD or AWD vehicle is really only needed if you have severe snow or ice in your area, and if they don't do an adequate job plowing. We have a nice AWD system on our Subaru Outback and it does great in Chicago winters. On the other hand, we've never had a problem or been stuck in any of our FWD cars, either.
Good luck!