Just make sure to use good glue if you lam 4cm, it will rip it apart if it doesn't pierce it right away, do ask how I know.
Just follow the books for the maintenance. As for feeds, if the part is going on a cnc then run it as fast as it will cut, if hand finishing slow it down to have less kerf.
I don't have a waterjet but get things cut on one sometimes. I have a stone shop. Is it the 87k psi one that you are getting?