No, I don't think all are signed by kent. Someone asked them on twitter how they can get a signed book, and they replied:
- Cdon, said the publisher.
I've found the link to the signed ones at cdon, but it only seems to be on the Swedish site, not the .eu one. Release date (according to this page) is 11th May.
It would be a great idea to sell them at the concert! Not heard anything about merchandise, although the tote bags that the people at the press conference were nice. Edit- I found a photo of one of the bags on Tradera (swedish ebay). 143554140_1.jpg