My experience is that people want to see things demonstrated that they can cook at home.
Gravlox is good, but use small pieces rather than a 10kg slab. For most home cooks, a half kilo is a reasonable amount to make and use before it becomes tiring.
The confit, although simple to do, is probably viewed by many home cooks as too complicated for home production — unless you’re doing a series on preservation and canning. Why not do something with the other end of the duck, instead? And don't forget about suggesting some side dishes.
The crême brulée is usally a crowd pleaser. Provide the audience alternatives to browning the top — even though it would no longer be "brulée" — since some won‘t use a torch at home.
Be sure to have copies of the recipes to handout and use lots of humor.