"Hooking the sail into the wind" means tilting the mast upwindof vertical.
Ideally, with modern sails that twist off at the top, having your rig nearly perfectly
vertical (perpendicular to the water overall water surface) is nearly always going to give you the fastest speeds (but I have seen some very fast sailors who do in fact hook the top upwind some of the time under certain conditions).
Why I am suggesting that you try this, is to get more vertical lift/force up off the water to help get your weight off the back of your board.
You are a big guy, and anything you can do to get weight off your board, and onto the mast foot (which pushes the board forward and keeps things in line) is a good thing at this stage of your skills building.
When your skills have improved, you are on sail sizes that support your size, it will be something you can correct. It might become a "bad habit", but not a bad habit that is difficult to correct when you want to go your fastest.
Simply standing up a little taller, changing your boom height, or adjusting your harness lines should correct for this, but you need to be fully powered up and have the rig supporting all of your weight when it's vertical before correcting the "upwind hook" is a good thing.
Right now it will help you get weight off the back of your board and help you to get planing.
Keep up the good progress.
As far as your harness hook riding up, what sort of harness are you using.... does it have upper and lower straps (a seat harness) to hold the hook height where you set it.
They all tend to "ride up" a bit, but making an adjustment for harness strap stretch, and
the natural "settling" of the harness to your hip shape, after you've sailed a few runs usually takes car of this, and soon your harness will fit you like a glove, and all the stretch will be gone on the straps and your harness hook will stay where you put it when you put your harness on and cinch up the straps.
If you are using a waist harness.... it takes along time for the harness to settle down, and the hook height is much higher in any case.
Hope this helps,