If you are buying Axiom on-walls or bookshelves, aim for the tweeter centers to be 3" to 6" below your seated ear level. If that's impractically low, you can raise them but you may lose some transparency.
On-walls also need to be mounted flat on the wall as they rely on the wall for bass response extension.
If you go with M5s, you don't need a sub but for sure a sub provides a benefit. Go without a sub to start.
As for fidelity while working in the kitchen, that won't be a problem. My kitchen is 20 feet away with a partial floor-to-ceiling wall in between. Sounds great!
Don't mount in the corners. Mount them flat where they'll give you the best presentation when you're doing 50% of your music listening.
