The only book left to be released on Pottermore is Harry Potter and the Deathly Hallows. A release date is currently unknown.
You can only move up a year when the next book is released.
No, you just can't move onto the next book until they've released it.
Once you've explored all the moments in the previous book, the next one should unlock. If you've finished a book and the next one isn't unlocked, then it probably hasn't been released.
You can only advance years when the next book is released. There's nothing you can do to speed that process up, it's entirely down to when the developers are ready.
It would be unfair to know the next Pottermore clue before it was released. You can find a list of all the clues and answers on the link to the Pottemore Insider in related links.
If you can't get on to the next book... JK Rowling probably isn't done with the next book. If you can't continue... Just explore the book that you just finished. Remember... Patience is a virtue.
If you mean book two, apparently early 2012
You cannot start a new book yourself. You have to wait until the next book is put online by Rowling and so far it is not known when that will happen.
As far as I know, we just have to wait until JK Rowling puts it on Pottermore, but I'm going to go crazy if she doesn't get it on there soon
Yes, Harry Potter and the Chamber of Secrets was released on Pottermore in 2012.
It's for the pottermore store and it is locked to all at the moment. It will open for ebooks and such in October.
New chapters are released when the developers are happy that they are completed. Announcements are often made on the Pottermore Insider a few weeks before new content is released.