Everyone always has ideas for the other episodes in the first season of their show. And that's great!
But honestly, none of that's gonna matter if you can't get the first show in the can. Don't announce as a series. Don't describe plot arcs or new characters who will show up later. Just focus on the first story, make it as awesome and as tight and as ironclad as you can so that it will excited people and then make it. Worry about the other stuff later.
Just my two cents.