The template for the tuck box isn't necessary. The rules actually state that you need to submit a three-dimensional mockup of an assembled box.
Regarding the EPCC standard courts, have you asked EPCC for them?
Regarding what you need to show, it's fully explained in the rules. Beyond those specifics, anything that makes your cards unique in some fashion needs to be shown, especially if it's unique in a non-patternistic manner - unique faces on all the spot cards, things like that. If it's simply a unique pattern for the spot cards, just show a sample of each value's pattern (or patterns, if there's more than one per value, such as for the 8-spot cards in both versions of the Mechanic Deck).