That sounds like a great idea.
The smaller chick is either a bantam or a runt. If you want to take a picture of it, post it in the What Breed or Gender is This forum and folks will help you with what it is. I'd wait until it has some wing feathers as some young chicks all look the same...
How well do you know the friend?
Normally, some folks would say two months is the best for quarantine. Realistically, I think most do two weeks. That at least lets you determine if there are any URI (upper respiratory infections), mites, suspicious poop, etc.
If it were a close friend of...