I am looking forward to see how this goes. Hitchhikers has always been a developing idea... The books were different to the original Radio series and the TV series different again. The Computer game was interesting and the Film of course was fun but some of the things in it were just plain bad - but by all accounts it was DNA's reworking for the most part. And it would have been a shame to just let the "universe" end the way it did - or didn't if you listen to the latest radio version ( more development ) - even Adams said that the last book was dark and well not much fun!
Paperback... 6 months generally. I try to get oversized paperbacks from the airport. I'd rather pay the hardback price for a paperback - At least it wouldn't put my luggage over the 20kg limit.