first film for mad max may set max up but it does little to show how crazy the world gets. Its why when people ask me about the mad max series i generaly say you can skip the fist movie as heretical as that sounds.

As for the fallout stuff, all those nuclear powered vehicles are in the world as is the energy weapons, power armor, robots, ect. 

As for rolls, hmmm

Glass boy: generaly a non combat roll. the scientest, medic, and schollar of a group. the one who can use old technology found in old bunkers, ruins, and elsewhere.

black finger: another general noncombat roll though that doesn't mean they dont see combat. Black fingers are of course in charge of maintaining,  repairing, and building vehicles. black fingers will ride along with gear heads and fury riders to do repairs on the go. example, your car catches fire because someone threw a firebomb at it, black  finger crawls up to extinguish the fire.

War Boy: your main combatants. they live for the fight. think future vikings of the post apocalypse. melee combat, ranged combat, unconventional combat, it's what they do best.  driving? not so much.

Gear Head: these are the drivers. the wasteland is too vast and too dangerous to simply travel by foot for the most part. this is where the gear heads come in. they drive vehicles to and fro.  this isn't strictly a combat class but they do see combat as raiders decide to come and give them  a bad day as they drive across the wastes. they get the war boys where they need to go and they generally aren't very good in a fight outside of their vehicle.

Fury Rider: a combination of war boy and gear head. just as adept on foot as they are behind the wheel. Fury riders are rare for the most part. 

you won't always be in your vehicle. inside ruins many times the vehicle won't fit and you'll have to get out to go dungeon delving.