Primary Office to determine whether 100% sourced wages for State filing

I have an agreement with my employer to work 60% at Home (New Jersey) and 40% at office (New York). Since 60% in NJ (>50%), my employer said it is a requirement now to withhold income tax from my payroll for NJ, and prorate my total Withholding tax between NY and NJ, based on the number of days or % worked in each location.  To enable withholding tax for NJ, the location of my employer has been changed to NJ address (since employer has an office in NJ, but I don’t work in that NJ office) in my earnings statement, however in W-2, my employer address is still showing NY address.

Questions: a) Is my primary or assigned office in NY or NJ? b) Am I subject to the NY’s Convenience of the Employer test? c) Is my 60% work from home in NJ considered telecommuting so should be counted as NY sourced income?