Yes, at 120 hz. Good luck running 4k@120hz on a 1080ti
Not on my island, I'm south caribbean
I'm not really sure I understand what you're saying. But in general it works like this:
Game --> SteamVR -->HMD (used in piplay v1.1.92)
Game --> SteamVR -> HMD renderer -> HMD (used in piplay v1.2.x)
So the first part is always the same: the game has to send 2 pictures to SteamVR: the left eye and right eye. So the game does its rendering and sends the 2 rendered pictures to SteamVR. However these are not yet suitable for displaying on a HMD. They would show perfectly normal on your monitor. But if you'd look at a picture like that through a lense it would look very weird because of the zoom properties of the lens. So what needs to be done is that the picture needs to be adjusted for the lens properties. This is called 'distortion. This can either be done by SteamVR directly (like piplay v1.1.92 does) or by the HMD driver, which happens in v1.2.x
You can check it btw, if you go to SteamVR and then choose 'display mirror' and then go to the displayed mirror and go the menu and select screenshot, you get screenshots that the game has sent to SteamVR so for the left eye and right eye. These are the 'undistorted' images, just the images that steamVR sends to SteamVR, these look normal on a monitor but would look weird through a lens.
So it's important to realize there are 2 'render processes' going on: a render process where the game just renders a left eye picture and a right eye picture and then a render 'distortion process' which takes those 2 images and 'corrects' them for lens distortion.
Here's a picture BTW to explain: http://d2rormqr1qwzpz.cloudfront.net/photos/2015/06/02/76715-47175-lens.jpg where the pic on the left is the 'undistorted' picture that the game sends to SteamVR. The 2nd picture is after the 'render distortion' that either SteamVR does or the HMD driver and the 3 picture is how that distorted picture looks through a lens (normal again).
Now you see the game it self is totally unaware of what happens after it has sent the left eye and right eye to SteamVR. It just knows it has to render a left eye picture and a right eye picture and when that's done send them to SteamVR.
In fact thinking about all this I don't think it has to be a problem at all: SteamVR asks the headset which resolution it wants and it tells the game to render in that resolution, for example 5120*1440. So this means it actually creates a left eye image in 1440p and a right eye image in 1440p at 60 hz and then the HMD driver distorts those and sends them to the HMD. But what confuses me is that 'brainwarp' process Pimax is talking about. I mean why would you not send the left eye and right eye to the HMD at the same time ? They belong together . But from what I understand they want to send the left eye image to the HMD first and then half a frametiming later the right eye image. That confuses me a bit ...