Do the police have a tendency do get stalked up on and attacked with the element of surprise on their side?
Both police and private citizens are assaulted by attacker who have surprise on [the attacker's] side.
Do criminals assume the police are armed when engaging in violence against them do they make the same assumption when casing a perspective victim?
What are the implications to your answer?
Do the police have a duty to de escalate a situation prior to a threshold for lethal force is met?
The police are absolutely tasked with deescalating situations when possible.
You are not the police. The engagement you are likely to encounter is just as different as if you were citing shootings in an active war zone to support your assertions.
Disagree.
In an active war zone you would likely be facing soldiers who are armed as such.
As has been pointed out, the private citizen and the police officer are likely to encounter the exact same criminals armed in exactly the same way. After all, many times the police don't show up until after the criminals have already preyed upon the private citizen.