-Any brakes and any hubs but you must use Hope brakes if you have hope hubs. You 'may' use hope brakes on other hubs (except shimano) only if you already own the hubs and wish to upgrade your brakes. All of this also comes under the 'King Exclusion Ruling' which states that you can, and I quote, 'use King with anything as it's bling'
-Skewers can be any variety (except shimano), but should be of matching or contrasting colour (not clashing - see anodising ruling further up) and must match front and rear.
-Maguras are allowed on a hangered fork as they predate suspension forks, ideally though the hanger should be replaced with an overly engineered bit of CNC to suit the germanic brakes.
-Finally, suspension hub on rigid - good (reminds me of when I was a kid and couldn't afford the forks but could get the hub, but I told myself it was the first step in the full Sus 5 year plan), skinny on a suspension fork- only when appropriate i.e. when used on a Ritchey P20 or similarly lightweight bike, or as part of a full XTR m900 set.
Hope that covers everything, now get out to your shed and make those amendments to your bikes quick-sharp!