Yes. That sounds way too long. Ideally, your intro is about a minute or two, especially if it has nothing to do with the characters or story and is just set up. I would think about a way into the world that involved the people we meet along the way. Or a few lines that summarize where we are now, sort of like they do in Blade Runner - then give us an opening scene indicative of the story of the show. Mad Men opens with Don trying to sell cigarettes...

You're copywriting the idea, not the spelling and dialogue. As long as the revision isn't a major overhaul, you should be good.

Most of the people I know staffed on shows are in their 30s and 40s. People usually come to LA, spend their 20s trying to break in, get a few solid breaks, and then get staffed in their late 20s and early 30s. Usually, that's because they work as an assistant long enough and get the clout to be trusted. Or that's how long it takes to get reps and to be read. I really don't think it matters as long as you're a strong writer who can get along well with others in a room. Plus, you need agents, managers, and all the rest.

I don't think there's an age imbalance - Writer's Rooms tend to have older and younger writers coexisting, especially if the show has an ensemble that varies in age.

I am HYPED

Glad you are enjoying it!