Game Version: I'm ok with this as long as its not used to sort the leaderboards any differently Having an extra column on the table is harmless. I don't see why not.
Segmented: Yes please. The majority of primes early runs were segmented and having that history visible on SRC would be cool by itself. Perhaps just having separate categories like "Any% Segmented" and "100% Segmented" would be the simplest solution. SS runs wouldn't be on these boards. "It's segmented but only one segment" is counter intuitive to the point of having a segmented listing at all.
Individual level's for segments sounds harder as not everyone will run the same segments and segments change along with routes.
Platform: I'd be OK with listing platform in our current boards. I'm not sure how useful it would be to have a separate sub-category for GC vs Wii