If I were you, I'd keep it simple and go with Option 2 that you have listed although you wouldn't connect wirelessly w/ Bluetooth, you'd connect with WiFi (Airport).
took this from another forum...it's what I used for my setup.
Steps:
1) Keep your iMac connected as it is
2) Go to System Preferences -> Sharing
3) Turn on Internet Sharing and select to share your Ethernet Connection with Airport.
4) You should then be able to have your AppleTV pick up your iMac's newly created wireless connection.
Hope this helps and keeps it simple and cost-effective.