Why you tried to change the kernel when there is no other working kernel except stock ??
You could try to force update:
-Go to: Settings>Applications>All
-Find: Google Services Framework>Force Stop>Clear Data
-Now go to: About Device>System Updates>Check Now
It should offer an update.
I think that for this action root is not necessary, but I'm not sure because I always root my android phone just hours after I buy them
And yes S Memo will no longer be available in JB. All memos will migrate to S Note, but if you prefer S Memo there is working version on xda, all you need is root so you can push it to /system.
Someone translate this to Italian.