Curious about Escort Services (not THAT one wizeguys!!)

How is the pay?
Do they prefer to hire CDL or former CDL drivers?
Do some outfits handle the permitting FOR the trucking company? One stop shop?
(After all, they're probably more familiar with local regs AND contacts than some out of state national carrier)
Is there any real requirement for a specific vehicle? (for years it was compact pickups but lately it's a lot of cheap 4cylinder sedans. Probably fuel costs are a prime concern)
Do escort vehicles have trouble matching the range of a tractor trailer? Even an Oversize getting 5mpg still has over 200 gallons aboard.
Most cars seem to have a range of around 300-400.

Just curious about a side industry I've never given much thought to.