NYSid,
Since StrataUS does the engineering I do not believe you will need an architect if you already have a design ready to be built conventionally. Since Strata requires certain items to be purchased from them you will need to submit plans for their engineering and pricing. Be sure to read very carefully ESR-1638 that you will find on their web site. That will give you a feel for what is involved using the Strata system.
Good Luck and let us know how it goes.