Answer 1

I'm pretty sure this causes an error, since you left out 2 in the conditional part of the for loop, and you defined count instead of loop.
But here's how it works:

loop and x both start off as 0. Loop gets incremented, then loop - x is displayed on the screen. 1 - 0 equals 1. Them, both x and loop gets incremented, and 2 - 1 (1) gets printed on the screen again, then again one last time: 3 - 2 (still 1)

(fixed code:)
var loop = 0;
for (var x = 0; x <= 2; x++) {
++loop;
document.write(loop - x);
}