I've seen a few posts covering bits of this but I just wanted to ask all the questions in one place...

I configured a BES Server for a client but they are already using the devices with BIS (Verizon)... Do I have to do anything differently to get their BES account going on the device? Will this sync their existing contacts and calendar with Exchange? I just afraid of losing any data that is currently there...

Any help would be appreciated, Thanks!

You are only as good as your last backup.

Backup the phone

Open outlook and move all contacts to a new folder in Outlook (this has saved me many times)
Export calendar entries to a pst file. Takes little time to do.

Then EA away.

Is this to prevent duplicates? Should I be concerned about Calendar items also? Thanks!

I dont use calendar much, but export to pst is a great way to back it up

Any other advice from anyone who has done this before? Thanks!