Caleb you start thinking about cast get the story right. I mean what is the theme? What is the arc of the character? How will he change? You may be able to achieve that in an hour. Don't tie yourself to a length or series, after all it isn't in your control.
My brother had a series on SBS, "Comedy School" they purchased eight shows. Halfway through production they dropped it to four. The show did great, rated well, Sydney Morning Herald had it down as the show to watch in its time slot. They didn't go to a second season.
This may sound negative. I just want you to focus on what is in your control. Writing a killer story. Once you sell it move on to the next one. If you are a writer (which is something you feel not do) you will have a hundred stories to tell.
PS don't worry if you think your story has element from other stories, everything does. Avatar and Dances With Wolves are the same film in different settings.