There is a separate Contacts app. When I synced my gmail account to the gmail app I also chose to sync my contacts and they populated the Contacts app. You won't see the contacts list within the gmail app but when you begin typing an email address while composing an email a list of addresses will be suggested.
If you did not already choose to sync you gmail contacts you can go that in the tablet setting under Accounts & Sync.
Sorry, I don't know anything about aol mail.