Answer 1

if p equals 5 then you will get access violation.

X=*p++;
X assigned value at address pointed by p (5), then p is incremented by 1

X=++*p;
value at address pointed by p (now it equals 6) is incremented by 1 and then assigned to variable X;

So X will contain value stored at address 6 incremented by 1.
But on PC you can't access memory at address 5 or 6 from application. You will get access violation if you do so.