I'll give BB and Asus a call very soon. I'll also talk to the vendor at some length - this time sticking to the point. (I don't suppose you've guessed my mind tends to grasshopper about.)
The W8 sticker is in mint condition, almost a square with the top tilted at the angle of the windows which change colour from green to reddish brown. Hard to forge I'd imagine. Not a hint of a Key in it.
The vendor pointed to a long number and bar code on the 'transformer' saying that was an easy way to see the Serial Number. Time will tell. I certainly have never heard of putting the SN in in lieu of a key.
Cars on Craig$list. I've sold three on there, including the @#$@$ Mercedes. In each case I gave the purchaser a list of tech info. The MB had an End of contract check at a main dealership, the buyer having been appraised of the replacement of almost everything over 20,000 miles. Now they even changed the hydraulically-damped engine mounts for good measure - all on my insurance. The bloke had owned it for about 60 seconds when the warning system told of a fuel sensor failure. $1,300. My team paid for that. So he was slightly better off with Craig$list than I was with the original MB Warranty which side-stepped nicely the gearbox failure - dumping it on my insurers despite it being a known fault.
Thanks for all your input on this.