Here are the top15 Questions for Sony from reddit ordered by upvotes - link
Will there be PS4 and Vita bundle?
Will the PS4 support mouse and keyboard?
With the PS4 functioning as a powerful Media Hub (besides pure gaming), which video formats does it support, and will we be able to plug in any Data device or will it only accept a FAT32 format?
I'd love to hear more about how Sony plan to use Gaikai. Will backwards compatibility to PS1/2/3 be possible through streaming?
Will you be able to change your PSN name?
Is the PS4 likely to have support for the Oculus Rift?
With the new Livestreaming feature, will the stream output only contain the Gameplay or will it be customizable to make it more personal.
-Will PS4 to Vita remote play functionality work while playing online multiplayer on the PS4?
-Will the PS4 still require double the memory of a game to install it like it does on the PS3?
-Will trophies instantly sync on PS4 like achievements do on Xbox 360?
-What will be the new friends list limit (if any)?
With the PS4 moving towards a more PC based infrastructure and the possibility for Indie developers to self publish, what are the odds of Sony and Developers allowing User generated content, or Modding, on the platform?
How will drive club PS+ edition be different from the full retail edition.
What is the maximum number of people you can have in a cross-game chat?
Will the ownership of games you own digitally on PS3 transfer to PS4 if they are made backwards compatible later in the circle?
How is PS+ going to change on Playstation 4 other than adding the ability to play multiplayer?
As in, will we still get 4-5 games on the instant game collection a month?
Ask about any details for the new playstation app.
Do they have any more details about how streaming PS3 games will work? Will we have to pay for any games we already own on PS3 again?
How many people can you have in a cross-game chat at one time?
Can we get more details on how the PS4's game recording technology works? We know the Xbox One has built in TwitchTV functionality; is the PS4's implementation similar to that?
Can you guarantee that PS+ will still retain all current benefits once it becomes necessary have a subscription to play online multiplayer?