Hi Amber,
Saw all your posts and I was wondering if you have managed to send the email via Marketo? We are trying to do something very similar to what you needed and we also want to add email scripting. The issue at the moment is that the data is not coming through, everything has been synched and enabled for Cases in Marketo and the Smart Lists are not picking up any values.
Grant and Cathal do you know if it is required to sync as well Case Contact Roles? It shows on top of Cases in the hierarchy.