1) Like I said, I only have two to comment on first hand. The Fujiyama has a cladding that I'm 99% sure is iron. Pure iron, unit : unit, is heavier than steel so it would make sense its heaviest. That said CKTG statistics have been wrong before. In the same vein, the Masakage dimension is likely wrong, and if it's correct, it's most surely measured at the tang/ferrule junction. I can't say as I don't own one, but I'm sure there's a distal taper. Not as tapered as you might be used to on a chefs/gyuto, but I can't imagine a 1/2cm spine all the way to the end before it drops into the thinner "tanto" tip.
The HD, in its light, thin, mono-steel form, is inherently going to have the most feedback, but these are all the crème de la crème. Anyone will impress you.
IMO, you will garner the best edge retention from the HD. As for sharpness - as you call it, HD & Shironiko both get crazy sharp. Its just a fact. Yes, maybe if you have the capability, albeit tools & skill set, you can get a slightly finer edge on the Shironiko, but even if that's the case... it's close. They'e both ultimately competent steels.
They're going to be easy to sharpen. The HD is thin mono-steel, and although you have to grind through jigane on the thicker clads, the Shironiko grinds like butter. Ultimately, its a real close toss up.
The Fujiyama is the coolest looking... to most.
The Yuki is refined simplicity; sand-blasted jigane, distinct cladding line, simple oval Wa, red ferrule (if you're into that).
The HD has the baddest aesthetics. No bullshit. No games. Practical perfection. (my totally biased musing
as I hate/despise/abhor bling - all I care about is performance).
But the coolest looking is going to be the Harner Hankotsu although it will be $400-$500 probably. I see Stephan Fowler is at the forge lately; maybe asking for a Honesuki is an option for you because that would cool looking & performing. Fowler mono-steel 52100. http://www.chefknivestogo.com/stfo15ho3.html