Okay, I posted the question
on the Amazon forums and the answer is YES about how to share subscriptions.
Leslie H. Nicoll says:
I verified it with my New York Times subscription. I, as the subscriber, receive it via Whispernet, but the other Kindles on my account can access the paper (7 days worth is maintained in the archive) via "My Media Library." You have to transfer it with the USB.
I would assume this works for a magazine subscription, too, but I haven't specifically tested that.