It's been a while since I flew to the US, but are these questions not *exactly* the same questions as the ones being asked if you fill in that green card that lets you apply for the visa waiver program?
It seems to me like they're just automating what was previously a manual process.
Plus, having the information readily available in electronic format, instead of boxes and boxes full of handwritten green cards, makes data mining and such much easier.
On the other hand, I've seen so many people making mistakes in filling in the green and white forms (despite the help of cabin crew), with the obvious result of being sent back to redo all the forms, and then join the queue for immigration again, that this will only make things worse. Apparently there are still people on this planet who cannot interpret a sentence "fill in a green form for each member of your party, including infants traveling without a ticket" properly. Should they be allowed anywhere near an internet-connected computer?
Approval is available right now, is valid for up to two years and is currently free of charge.
I find this two year validity a bit confusing. When you apply for the visa waiver program you've got to identify how you got to the US (carrier, flight, city of boarding) and where you'll be staying in the US. I have not met anyone who knew this information two years in advance. And for multiple trips to the US, originally you had to fill in a green form every time you flew -
AFAIK even if your trips were less than 90 days apart. In other words: you had to apply for the VWP each and every time. I don't think that procedure has changed now.
Airlines, apparently, will not allow anyone to board their aircraft after this date unless they have the pre-approval document in their possession.
The way I read the FAQ is that there is no "approval document" which you can have "in your possession" as such. Everything is electronic and the airlines will have an automated way of checking that everybody on the flight either has a visa or is approved for the VWP program, presumably based on their passport number and maybe some other information.