The AIM says a VFR on Top aircraft should 'advise' ATC before making an altitude change and it's listed in the reports to be made at all times in the Instrument Flight Proceedures handbook. The AIM also says ATC may provide traffic information but will provide separation in Class B and C. As to route, you've been told to maintain VFR. That means avoid clouds and other aircraft. An airway is 8 miles wide, if you've got to turn 4 miles for traffic you're in the wrong airspace. If you were on a regular IFR clearance, would you wait till you could get a word in to New York departure if you thought you were going to hit another aircraft?