This is going to look amazing. Particularly with the rock work - once the crevices start to develop a bit of algae, it'll look crazy good and will make the stone pop a bit.
Sometimes hair grass needs to be trimmed a bit once planted in order to encourage new growth.
That's good news about the filtration insert. For the price, it just makes more sense (especially with the strong-ish lighting) than to use the other similarly priced all-in-ones.