I don't really have a clue what I'll be putting in them, so I'm not sure what shape they need to be. I think water mainly as the Kona has only one cage and I don't like sweaty backs.
If it’s just water, better off underneath the down tube or on the seat stays, using hose clamps.
Heavy mass on bottom of bouncy forks does make bike handle weird, only worth it if you’re out of space elsewhere on bike
Yours will 100% look better.
They need to be long, not particularly wide. Long is useful.