A1. You must have a data connection to calculate routes and download maps, although you do not necessarily need a constant connection while following the route. Maps are precached several miles ahead of you along the calculated route. Rerouting calculations also require your cellular network. Additionally, you need a connection to purchase and use Live Voice Guidance packages.
If you have any trouble getting navigation and maps to work, it's a good idea to check your iPhone's network connection.
A2. Certainly. If you would rather not use your data connection while driving, you can download maps along your intended route by using Simulate & Pre-Load Maps. You can use your iPhone's WiFi connection as an alternative to your carrier's data connection.
Keep in mind that only map tiles along the calculated route will be downloaded during the simulation. If you detour from this route while on the road, map tiles will be downloaded for your current location on the fly.
On the Location Details page touch "Navigation Choices". Then touch "Pre-Load Maps" and then choose either Pre-Load or Simulate and Pre-Load. Either method will save the map tiles along your route before you begin your trip.
A3. Yes, although the performance of MotionX-GPS Drive over the EDGE network will not be as fast. Rerouting calculations may take significantly longer, and maps will not download as quickly. However, MotionX-GPS Drive now stores map data ahead of you along the calculated route, so in most cases you should be able to see your maps.