I also pull the laces down towards the blades. I never have to retighten....my old skate tech told me they stay tighter that way (also if you pop a lace somehow they hold a little better?). I think the staying tight may have to do with the extra little loop you get around the hook.
In the past, I always skated with all the hooks done (post-break in). And I certainly could not have done otherwise in my old, but still pretty stiff skates- they were broken down just enough that even for dance, I wanted the support.
Now, I'm in dance boots (Risport). They are lower, so my top hook corresponds to the third hook on my freestyle skates. Now, I'm still adjusting to them, and haven't tried jumping, I don't think I'd be afraid too. BUT in the break in phase I did try leaving the top hook (so the equivalent of the 2nd on free boots) undone. It was scary, and lasted less than a minute- the time it took me to stroke a couple times and hurry back off the ice. Given this, I think if I ever went back to free boots I'd be just fine, and may prefer to stop at 3.
So, I'm agreeing with everyone else- if you're more comfortable stopping at the third hook, do it. If you find down the road, like SarahSpins did that you do want that 4th hook, you can always go back.