Don, I don't think #3 applies to anything, because unless his parents press charges, he can do whatever he wants to the family's own computer.
Just tell your dad your predicament, I had the same thing growing up. I got him to MAKE me administrator because he was sick of having to type it in 5+ times a day.
If you REALLY need to bypass it, you can do it without hacking by using the computer via your dad's account when he leaves it up, and simply changing permissions so that admin passwords are not required for downloads.
Or you can follow whatever guide Moon.exe sent you (which by the way, is not against our rules to post).
I used to know how to bypass login passwords on 95-XP (it was really easy) but they actually took the time to make Win7 more secure. Who woulda thought?