Hi,
1) I thought that I do Not need to get a Passport Stamping since this is an intermediate step.
--take infopass, go to local USCIS office with I-485 approval notice, passport I-94 card, all EAD AP and 2 passport photographs and get passport stamp and they will take your fingerprint and signature on white form and will send that white form to service center to make card
2) What is the cost/filing fee of passport stamping and ordering plastic GC?
--------none
Thanks