The ambitions are actually HEAVIER the icons, why? Because the grooves on the icon are cut into the wood which dramatically reduces the weight, while ambition have their grooves cut into UHMW after it is put on the board. The result is the ambition board has a higher concentration of a heavy material which makes it heaver; both methods have their pros and cons though.
And lastly the icon snowskates base is made out of UHMW and the reason why they used a sintered UHMW is so that you can wax your board so it performs like new every time (ambitions boards cannot be waxed so you have to use a scrapper to get rid of any gauges but this method does not make your snowskate perform like new every time.
Yes, you are correct. You need 8 plies with the cut-out wood channel design to get 5 or 6 complete plies (Premier, Icon). The Ambition design requires a thicker base sheet to make the channels. I prefer the channels cut out from the base with a router because it guarantees the sharpest groove cut and the best tracking from my experience. The way the channels are done makes an Ambition and Ambition, and is what differentiates Ambition boards from other wood snowskates on the market.
Ambition boards do not have waxable bases for two reasons. First, its literally a maintenance-free board. I'm no expert at waxing, and don't have the first idea about different waxes for different temperatures, others who snowboard a lot may really want a base they can wax regularly. Second it gives the most predictable, consistent performance over the life of the board in a variety of conditions. From my experience ambition bases never become slow if you treat them well, all of mine are still fast as f**k.