Do I need to have played Myst in order to play Riven

I've done some looking around and it seems like the best way is to run it inside a virtual machine. Posts I've read are suggesting Virtual PC, but I suspect other ones (like VirtualBox) would work, too, so long as they support running QuickTime.

Your gaming experience might not be all that great on a virtual machine, but I don't see Myst being so demanding on resources that it'd degrade horribly.

If you're running Windows 7 Professional (and up, just not Starter, Home, or Home Premium), you can download XP Mode, which is essentially an XP VM that you can use free of charge. With other virtual machines, you will need to install a copy of Windows on them, which means you will need a valid license key (or beat the game in under 30 days if you're installing a version that requires activation).

I seem to remember that The Stranger finds the Myst book in the stacks at the Chicago San Francisco Public Library. I don't remember where I read this, but I think it was in the separately-published hint guide.

How the book arrives in the Library is explained (sort of) in Riven: The Sequel To Myst.

Atrus, the man you meet at the end of Myst, once lived with his wife Catherine and his father, Gehn. All three were able to write Linking Books (books which link to other worlds). At some point, Atrus and Catherine realize that Gehn incorrectly believes he is creating the worlds in the books rather than simply opening doorways to already existing worlds. Atrus and Catherine determine that Gehn is a danger to the inhabitants of these worlds, and they decide to trap him on Riven, a world without the ink or paper necessary to write Linking Books. Riven contains a location known as the Star Fissure, a portal which (unknown to anyone) leads to Earth. Atrus and Catherine destroy all but one of the Linking Books on Riven, and then escape to Myst through the Myst Book, holding it over the Star Fissure so that when they link through, the Book will fall into the Fissure and be lost. Their plan succeeds and Gehn is trapped on Riven, while the Myst book drops through the Fissure to Earth, where it is eventually found and used by The Stranger.

Atrus mentions this event in his opening narration:

I realized the moment I fell into the Fissure that the book would not be destroyed as I had planned. It continued falling into that starry expanse, of which I had only a fleeting glimpse. I've tried to speculate where it might have landed, but I must admit that such conjecture is futile. Still, questions about whose hands might one day hold my Myst book are unsettling to me. I know my apprehensions might never be allayed, and so I close, realizing that perhaps, the ending has not yet been written.

Little to no detail is ever provided about The Stanger. This is intentional, as it allows the player to experience the world as themselves, rather than forcing the player to take on an unfamiliar and therefore less immersive role (such as a space marine, theoretical physicist, or black Scottish cyclops).