Think of it like this
Kies is to Samsung as iTunes is to iPhone
With Kies, you can play music, but also back up your phone (contacts, etc.), add music and photos to your phone, and upgrade your phone
The benefit with the Galaxy S3 is that you do not have to use it, as you can transfer music to your phone via USB cable to the computer and drag and drop music to your phone. You do not have to use Kies, its optional really (unlike iPhone where iTunes is required to do anything...eck!)
I never used Kies...I have tried it one time but I never use it ever
If you have contacts you want to sync from Outlook with your phone, you can just export the contacts from iTunes as a ".CSV" file and import them into your Gmail from your coputer, and your contacts will automatically come on your phone once you sign into your account on your phone
Here is how to export your contacts as a CSV file
How to Export Your Outlook Contacts to a CSV File - About Email
Once you do that and save the CS file somewhere on your computer, go into your Gmail, then click Contacts
Once your in Contacts, click "More" and then Import...locate the CSV file and your contacts will automatically be attached to your Gmail...so then they will automatically be synced on your phone once you log in