My Verizon USB 727 from Novotel is recognized by the tablet, led initially red then goes green and I see usbtty device in the /dev/ folder. So, it seems the USB port of the a500 can support the modem...question now is if there is drivers and propper ppp chap scripts to get it working.
Found this thread which I am following along and will post back if I have any success. I did find that I had to plug the usn dongle into my windows pc and connect to the com port of the modem via hyperterminal and run AT$NWAUTOINSTALL=0 and then AT$NWAUTOINSTALL? to verify that the usb drive capability is turned off...apparently linux/android OS doesn't like this and wants it to be "only" a modem.