Don't know if you've found the answer elsewhere or not -
For contacts, I'd begin in Address Book on the mac side - select all, export as Vcard.
Go to gmail on the web, contacts in upper left corner, then other actions drop-down button, then import vcard, then delete duplicates.
Go back to the Mac side, Address Book prefs, choose accounts, then sync to Google.
Also on Mac iCal, prefs, sync to Google.
For music playlists, many seem to like the Doubletwist app - I just use drag and drop, it seems easier to me.
There are also some apps sold that will automate all of this - hope this helps!