A book can be a good idea, useful for if he needs a little down-time - depends on what they are doing on the camp. Most Beavers will play footie or a game if there's down time, but no harm in packing a book in case.
By very little information, I mean I've been given a list of clothes etc required. Nothing else
Out of interest, what else were you hoping for? I'm a cub leader, and usually give very little info out before camp, except drop off time, pick up, and a kit list. I might give an indication of the sort of activities we will be doing when advertising the camp, but nothing much after the initial info. I certainly don't give out the menu, or a list of who's in which tents, or a full break down of activities. It only causes problems with parents telling me "Freddie won't eat that, Johnnie will only attend if he's in the same tent as George, Jack won't want to do tunnelling". In the actual event, Freddie, Johnnie, George and Jack will probably do everything, eat everything and will sleep so well they won't care what tent they are in.
Trust that your Beaver leaders will know what they are doing, and your DS will have a wonderful time.