In answer to the specific questions:

I prefer to board last (standing in line anywhere is something I only do if it is absolutely unavoidable), but when overhead space is likely to be insufficient to meet demand I will try to board as one of the first. Proper enforcement of hand luggage weight, size and number restrictions would certainly help in this regard.

On fairly empty flights boarding last also allows me to pick any vacant seat, instead of taking my assigned one in a row which the airline is almost guaranteed to have crammed full in recognition of my LTPE status.

The last question is worrying, it conveys the impression that KL is already having second thoughts, before they have even managed to properly implement SkyPriority boarding.

Regardless of which system they choose, they ought to have figured out by now that the key to smooth, efficient and timeous boarding is to get the gate agents to actually do their job properly. It ain't that difficult, and I think that might even be what they are paid a salary to do.

So . . . what is KL waiting for?

Johan