Icloud on Imac

[mich]

I just bought an IPad2, have an iphone3gs, Imac 9.1, Macbook Pro early 2009. I installed Lion on the Macbook Pro, updated my Iphone to icloud on my Imac in ITunes, then installed Ox s and Lion. It wiped out a book data base because it was a PC/MAC version, and did not update Ical or Address Book. I also have time capsule, which shows back-ups from August 2011 back, nothing current, it is on daily auto backup. Can I uninstall Lion will that enable my to use old data base again? Also how do I get the mail to become a split screen, please. Thank you, mich