I think you're stuck with Monty and Mitch/Foles. You must fix the o-line. After that, you can worry about the other positions. Otherwise, you're putting fancy shingles on your house and your foundation is collapsing.
With an above average o-line, you can run successfully with Monty. No 98 yard TD runs, but he'll get decent yardage if he isn't hit behind the line of scrimmage regularly. The QB gets a pocket to throw from. You may lose to the really good teams, but at least you can hang with them and potentially out scheme them.
I'd love to get a better QB, but with the current line and coach, what's the point?