Not sure I follow this. If you're in a situation where striking is appropriate, victim selection has already occurred: the attacker is within striking range and has committed some overtly threatening act.
Not necessarily. There is the obvious action that I may initiate the strike as a preemptive means of controlling the situation. Also, just because the preventive decision did not come out in your favor doesn't mean you cannot strive to change back those odds to your favor.
If you fail the initial preventative decision (i.e. you are attacked), there still exists a duration of time during the attack when you can deter the attack (i.e. fight back). The duration of time is dependent upon your ability to withstand punishment before you become incapacitated (or the attack ends). This is your "self-defense" time. The focus of your actions has shifted from preventing an attack to deterring the continuation of an attack. It is during this period you have an opportunity to convince the attacker the cost is greater than the benefit (i.e. stop attacking).