Thanks, at least that clears up one question
I've found in my Email Groups a "Subscription List Data Lookup Id" which I'm just trying to figure out how I can use now... half a step closer perhaps
I now Finally have it working!
Under Settings > Setup > Website > Web Data Lookups I created a "Contact Group Membership" lookup and grabbed the scripts from Data Lookup Options
The GUID I used was found under Settings > Setup > Assets > Email Groups - click on the little "i" icon next to the name to get the Subscription List Data Lookup
This post helped me lots: Sample script to populate checkbox on an Eloqua10 form.