New user - looking for info & a few how to's & Iphone?? Looks great though!

[virtualu2]

Hi,
I was wondering (Note - I read some posts and some items were covered but related to older versions).

1. How does zimbra desktop compare to thunderbird or outlook I guess...I don't see going back to outlook though.
2. Are there "add-on" type things for tasks like "quoting" in replies to emails, or such?
3. IPHONE synchronization - is there a way to get my contacts, calendar, and tasks to my iphone? Even if I have to use a couple things to do it?
4. How can I export my email, contacts, notes, etc and be able to import them into another mail client if I decide or "have" to switch due to work policies?
5. I ran the installer and got this error, but things look OK? Should I be worried?
/usr/share/themes/Human/gtk-2.0/gtkrc:51: error: lexical error or unexpected token, expected valid token