I'm really sorry, I forgot to say that we're using EJB3 and annotations.
Our cluster will be load balanced, and one of the problems related to this sort of things is what you mentioned.
About your solutions I must say that about the cache we're thinking about it and there's another open discussion on this forum for another problem we're having;
The second one has been also considered but we're keeping it as last resort.
Thanks a lot
Ale