Yo,
Classic and iso are pretty much the same except for the obvious, i think maybe the flanges are longer on the ISO though. You will only need a steel driveshell if you run a single cog as opposed to a cassette i think. The HD axle and fun bolts come as one and will make your hub stronger, although if you wait until you break the standard one then CK will replace it with an HD one for the price differance between the two. Whoa i'm a fountain of knowledge lol, especially considering i don't own one lol. Oh and buy from aspire velo tech on ebay :)
Pete