[subject] + 一会儿 + [verb] / [adjective] + 一会儿 + [verb] / [adjective]
一会儿 A 一会儿 B means "A one moment, B the next". The two keep swapping, and the speaker is often a little impatient with it. Each 一会儿 goes straight before a verb or adjective, and the two are usually opposites or at least different.
There can be more than two, and the parts can be longer phrases with objects.
With two different subjects, each 一会儿 comes first in its clause.
一边…一边 is two things at the same time: eating while watching TV. 一会儿…一会儿 is one after the other, switching back and forth.
The wrong line has him driving, then stopping to listen to music, then driving again.
On its own, 一会儿 is "a moment": 等一会儿 is "wait a moment".