[Karthak]

I'd chalk the "near-light speed" thing up to http://tvtropes.org/pmwiki/pmwiki.php/Main/ScifiWritersHaveNoSenseOfScale

Without FTL plenty of the pre-Damocles Crusade fluff in the Tau lore makes absolutely no sense. No way they would have been able to withstand the Imperium if they couldn't travel FTL.