1) Oh god no.
2) Is Tom Bombadil the original mystery box?
You don't have to tarnish the old heroes to elevate the new ones, all that was needed was for the new generation to protect what the old one had built: basically, don't have the New Republic fall (nor Sidious come back).
That's not on Johnson, Abrams was the one who wanted to have her arc all in the first movie.3) Give Rey a character arc. Don't simply start her off as all-powerful. Allow her to start as a promising candidate and become a badass superheroine over the course of the three movies, as in the OT. Give her weaknesses and flaws. Give her a Leia-like mentor if you want to make this about female empowerment so you don't have her under the wing of a male Jedi master. But allow her to be a nuanced character with both weaknesses and a character arc, don't simply start her off as superwoman.
Finn.4) Flynn the former stormtrooper shouldn't be a joke.
Despite the name, Star Wars is as far from military Science-fiction as Science-Fiction gets. I mean, the main characters use mêlée weapons. Aesthetic definitely prevails against tactics there.5) For pity's sake, bring in someone who understands military SF and tell a decent story for episode 8 rather than the ridiculous chase we got.
Maybe look into Kyle Katarn from the old EU? I'm not sure how much that part of his character was touched on in the games he was created for (I've only played the last two and it doesn't come up) but he's in books and stuff too.
That's not in the Thrawn Trilogy, he still tries to get more training in these books. Are you thinking of something else?