Oxford cloth is a cotton woven in a basket pattern, with two threads crossing two. That gives it a slightly textured surface and more body than a smooth poplin, so it looks good unironed and keeps its shape through a long day.
The collar
A proper button-down collar should roll, not lie flat. We cut ours a little longer at the points so it curves gently over the collarbone whether you wear a tie or not.
Washing
Wash at 30° and hang it up straight away. If you want it crisp, iron it while it's still slightly damp. If you don't, the creases will drop out by mid-morning.