Hmm, I think they preload first, because loading on the fly would hurt the animations. Actually the site only took 10secs for me to load and the content is more then worth it. I've seen much much worse sites concerning loading time, even very pro ones.
You also have to look at the target audience here.
They are located in belgium, where as far as i know, the connections are really fast.
Keyboard navigation would be a nice feature, but fairly said, i haven't meet anyone yet who doesn't use his mouse surfing on the web.
They do use a flash check and the site is made for flashplayer7, which penetration is almost 100%.