Hello to all and sorry if it is a stupid questionbut:

Can I start the base campaign with the investigator from the Dunwich legacy using the investigator's cards from the various mytos pack?

Sure. You can play any campaign/scenario with any Investigator, and use any cards from any Mythos Packs to build your deck (mind the personal restrictions for the chosen Investigator, though).

Yup, just remember if you're doing a campaign, you're supposed to only start with 0-level cards. That's the only restriction.

And just remember, no question is a "stupid" question. That's what these forums are for.

thank you all!