GPS was discussed in this topic. Have you tried the methods in that thread (there are two ways to do it, one using the HTML5 Geolocation feature and the other way is using COMM (serial) communications.
RFID was also discussed in this topic. At this time you can use RhoElements on a RFID handheld like the 3190Z, but cannot access the RFID reader or tags through RhoElements. At this time A NPAPI plug in needs to be provided in order to use these features.
Thank you Rob