Re weight distribution:
In light weather move as far forward as you can, mainly to get the stern out or up as it were - The bows should definately be in the water. In super light stuff I skipper on the windward hull sitting in the spot between the sidestay and the front beam leaning forward with the crew on the leeward hull in about the same spot.
As wind increases both are on the windward side sitting on the hull, crew up next to the beam and skipper close behind pretty much either side of the sidestay.
More wind, one on wire either skipper on side against sidestay and crew out with front foot on the front beam (ish) or crew in and skipper out at with front foot about sidestay. Just depends on which of you are heavier and what the breeze is doing. My crew is lighter than me so if there is enough wind to have one out some of the time then I get her to trapeze in the puffs whereas if the puffs are a bit stronger and you sometimes need two I'll be out.
More wind, just twin trapping - move back a little bit depending on what the water state is like.
More wind, comfortably twin trapping - I'm trapezing a little further back about in line with the middle of the centreboard and the crew either side of the sidestay. Some people trapeze a little further forward but it all depends on what seems to work for your sails and how heavy you are and where your weight is distributed between crew and skipper.
Sea state comes into play as well when the wind gets up so if you find that you are ploughing into waves too much or getting wiped off the side move back even further. I've sailed upwind on one or two occasions with my back foot near the back beam but that's pretty crazy stuff!

As for sailing solo, can't really say with any great confidence but I can remember trapezing further forward when going upwind and further back off the wind. Oh, and being totally out of control (but that's another story)

Where the rocker is determines where your weight is distributed and the hull shape changes most around the centreboard case or just in front so downwind its the same as upwind:- in light stuff stay right forward leaning over the front beam and gradually move back as the wind increases.

Hope this helps!