Rotation b/c on front wheel drive the front wheels do all the work (power, steering, and primary braking), while the back are more-or-less along for the ride.
On a rear-wheel-drive, the fronts brake and steer, while the rears do power.
(That is an oversimplification, but it gets the idea across. Both also help on cornering grip, weight carry, etc)
On a a Front-wheel-drive, if you didn't rotate the fronts would wear out FAR faster than the rears.
As for alignment, there are several reasons, esp. if they don't know how the vehicle has been driven. A misaligned vehicle gives uneven wear to tires and can affect handling, power-distribution, and cause odd braking. It gets misaligned by hitting and running over stuff.
Some vehicles are more sensitive than others to the alignment getting wonky.
As a shop, doing it ensures that all-is-right and a customer won't leave with a miss-aligned car (opening them us to a lawsuit). Also, it is extra cash, as most cars don't actually need one.
It's good to get it checked ever-so-often. I do when I get new tires. Many do it WAY too often, while others do it almost never . . .