Don't know about the conversion. Maybe someone else can advise on that. But if you have your contacts in Outlook, Yahoo or some other PIM that Desktop Manager can work with, syncing the blackberry with that is your best bet.

About the ringtones, see

How to Convert Ringtones - BlackBerryFAQ.com

What kind of ringtones/audio can my Blackberry have? - BlackBerryFAQ.com