You're moving the stitches around in order to get the right number of stitches in the right place for you to knit the heel flap.
RS in the round is the outside of the sock; WS is the inside.
I'm going to try to answer your last question, but I don't think I'm going to be able to explain it very well.
If I'm picturing it right, you need to turn your work so the inside of the sock is on the right side of the needle holding the heel stitches. Because the heel is worked flat, which side of the work you're on matters. If the wrong side is on the right (along with the sock), it means you're starting the right way. If the wrong side and the rest of the sock is on the left of the needle, you need to turn it.
Hopefully someone else will be able to help you more with that last part if I just confused you more :oops: