Not if you're using it just for the wayfinder maps or any of the free navigation software provided for the tablet. Yes, if you buy the wayfinder maps with includes gps routing and voice directions. In other words the gps is useless without some kind of routing software.

No wi-fi needed to use it with the built in gps, although a wi-fi connection helps in getting a quicker sat lock fix.

Never used rhapsody with the N810, but it's probably a subscriber service where you can download and listen to music for a monthly fee.