All I can say is: Good luck.
Enough of the OOTB fittings are inaccurate that you really need to check over them all. Alot of the content (fittings) that I've found so far from manufacturers either is very old and needs updating for the way Revit works now or wasn't really set up all that well in the first place as far as I can tell. (take this all with a grain of salt; I'm working through my second Revit MEP WWTF project, and our department only got Revit in October)
For fittings, most of what I've added to the OOTB stuff is stuff either I have created based on an existing fitting, or our reseller has created for me/ helped me out with.
As for pumps and pieces of equipment.... about 80% or so of our suppliers are able and willing to provide .stp files of their equipment for our use. (the other 20% I've simply modeled in autocad and imported into Revit)
