Valve's documentation highlights the different ways standalone games run on Steam Frame
(www.gamingonlinux.com)
Not yet. Although some people say it'll be close to the price of an Index although it's still all speculation.
I'm reminded of an old Simpsons episode: https://youtu.be/UUc9Ojfxq3E?t=106
Bart: "How much do those yoyos cost?"
Milhouse: "I don't care"
That's kind of how I feel about this.