Average height of a first cross? out of the two you put up 24" 26"
Are they fast enough for a fox one out? yes they are
How are they with stock and animal proofing? same as any other dog teach them young
Are they prone to dog or people aggression (i work with off lead non-aggressive parsons bush and den) ? no there no aggressive to people or dogs they wont take shit from a dog also but tend not to start it hope this helps