well i just registered after reading the whole thread, really like it and like the theories you guys proposed, here's mine.
First of all Jiraya is DEAD by any means, remember tsunade said "he's not comming back" and said she would accept his proposal next time as she felt it, plus there is no way jiraya can survive such a blow and frankly if he did it would be unrealistic from the writer, he had to go.
The message he gave to pa was pein's true identity and other secrets about the nine tails and probably the nine tails key - there is no doubt that pa will feedbak the frog king and also probably the king will summon naruto to explain jiraya's purpose and naruto's true bloodline.
now as for the sasuke itachi thing, i have a guess but it's very twisted but i'm really somehow sure that itachi is not behind the extinction of the Uchua clan.
i think he will reveal to sasuke hidden clan secrets and probably someone else was behind the masacre and itachi was trying to stop him/her but didn't do it in time. my guess would be also pein who did it and uchua midara was behind it and he killed him and thus obtained the mag sharingan, however, i feel that itachi made sasuke think he did it to make him stronger. i also think itachi will die protecting sasuke which will probably fill him with rage that just when he found his brother's true intensions, itach dies- which would lead us to the point that now sasuke and naruto have the same motive which is to kill pein for revenge.
it's just my opinion though.
=) have a great vacation guys