Good luck with your championship aspirations. As someone who has been heavily involved with our domestic championship for well over a decade I can tell you it is a lot of work but can also be rewarding.

Your ideas are fine. All tried and true activities and used by others for many years.

Presumably you are looking to promote the championship but other organisations are running the events? If this is the case, make sure you meet with organisers and determine, jointly, the prescriptions for a championship event ... what is do-able and what is not.
Communicate, communicate, and communicate again. Listen to your organisers. They have the bigger job and will have much more at stake.

Define and understand the purpose and focus of the championship from your ASN's perspective. What are they wanting you to achieve?
Who are the other stakeholders and what are their expectations?

And remember, when it comes to competitors, there's a lot of "gunna's" out there.

Of the initiatives mentioned, in town super specials can be good but not every event has a suitable or affordable venue.
The same applies to things like ceremonial starts.

I don't know what categories make up the bulk of your sport in Norway. I would have been surprised if it was 2WD dominated. I'd be quite wary of choosing R2 as the promotable category otherwise.