Hey snowizard, I don't know from your profile what region you are grooming in, so what I about to say may not entirely answer your posted questions. I have groomed primarily in the Rocky Mountain west, and if we have found out one real truth in snow surface prep, it is that the more you groom it and ski it, the harder it becomes. At Copper, we like to stay off of the tillers until the groomers just can't stand the finished product any more. Our primary implement is a wonderful Pisten Bulley offering called the "Super Bar". We articulate off to one side which helps to break down any hard track or blade chunks while keeping one of the folding wings up (obviously to the ungroomed pass. This technique requires that all of your operators including the rookies become quickly adept at shallow surface blade dozing.
Regarding the other components of your question, especially wet snow/rain grooming, I would defer to my esteemed colleagues in California. Several guys including Todd Rudis from Heavenly came out and made a wonderful presentation on this at our Colorado Ski Country Snowmaking and Grooming conference last spring.
Otherwise, I've got a 2 credit hour course starting January 12th that will cover all this in detail...