Greetings mike,
As far as contacts go, If your device is synced with your google account, then your contacts are stored on Google's server and will restore when you reconnect your account.
I'm not familiar with your phone, but if you go into the contacts app and select the menu key, you should have an option to export your contacts to your memory card. This way you can have a hard copy that's always available to you as well.
For texts, I use the app SMS backup n2manager. It will allow you to backup and restore all your messages.
I don't use my gmail account for my emails, I use yahoo. So I'm not sure how to tell you to backup emails, as mine always reside at yahoo and I access them through their app.
Unless your installing a more updated version of the same ROM, you most likely will lose all of your system settings, because you have to wipe out all data a caches.
Titanium backup, Super manager or Mybackup will allow you to save your apps and their data. Just make sure that you don't restore system data between ROMs because that usually causes problems.