We kill adds as they spawn, but wait for tank to get hate before doing so. Our tank has a pt chat macro he uses when AoE hate is established via /blu so dd's don't get themselves killed and geos can cure tank for the bubbles to hit adds. It makes things a lot safer and more organized in my opinion.
Quick note on thf, using larceny on SV will not prevent chsrm fest.
If you bring a rdm, you won't need 2 whms so for a 12man fight id go something like... whm geo dd x4, brd geo tank rdm and maybe 2 pet jobs with prefight cor rolls from a mule. Other than pet jobs with prefight rolls from a mule, those last 2 slots are going to make your life more difficult.
Last thing is bring lots of pops. You don't have to be near a warder NM to get its key item, so mass farming multiple NMs at once can speed up the process greatly. Even the best groups, aside from conduit burns, can still fail WoC sometimes if he just says F U repeatedly. Sorry if some of this info is obvious or repetitive, but they are things i didn't learn until after the fact.