Welcome to the forum, It depends on which CCV mod you are talking about, if it is a provent I suppose they could hassle you about the warranty for emissions equipment or anything else they can tie it into but I think some people are getting away with it? Open vent is illegal to begin with I think and will not make dealer or epa happy. But again i think some are getting away with that too. Wont comment much on the oil except to say CI 4+ full synthetic, 5W40, there are others here that know much more than me about all this stuff so I will leave that to them.
So tell us more about the CAT oil. Does it have the CI 4+ rating?
Here is a good post from another thread. EHM is elephant hose mod aka open vent mod
General advice here (I was a newbie 3 months ago) is to:
EHM
Change your oil after a few 100 mi. to a 5W/40 synthetic like Shell Rotella T
Keep your OEM tires at around 40 lbs. for best mileage
Keep an eye on your air filter (changed mine @ 4000 mi. to a Wix: HUGE difference)
Get a straight through muffler (magnaflow, flowmaster, aerodyne, glasspack)
Don't let the tank get below 1/4
Feed it a little biodiesel occasionally to keep it quiet and clean
I think that summarizes the advice I've gleaned. Oh, and read the L.O.S.T. KJ forum regularly

Mine has a BD in April 06 and no problems so far (7000 mi.). You may have a late enough model that Chrysler fixed
most of the big problems before you had to deal with 'em.