1) Yes, you are allowed if you are RNAV approved and can use that without the requirement for conventional navigation backup or if you can replace the required fix by other means of conventional navigation (VOR/DME aka radial and distance). Most classics are not approved to use RNAV without conventional navigation backup, on NGs that is normally not a problem if you have 2 GPS and 2 FMCs. However specifics are a question of the approval your company holds and the rules laid down by our local authority.