Nokia :: Assisted GPS (A-GPS) / Data Transfer

I am using my Nokia E71 as GPS. I am using "Integrated GPS" & "Assisted GPS".I am using a 3G access point from my provider. I noticed that I get a GPS connection in a few seconds almost anywhere (inside & outside).
This is because of the A-GPS.I know A-GPS is using the 3G network to get faster GPS connection.

Here is my question:
If I start Nokia Maps (3.03):
+how much KB will it use on the 3G network (for example when navigating to a location)?
+how long will I be connected with the 3G network (for example when navigating to a location)?
+will it be using the 3G network (downloading & sending data) all the time when Nokia Maps is open?
+is this going to cost me much to use this? If I open Nokia Maps 3 times each day.

After I get a GPS connection, will it stop using the 3G network (no more paying for kb data or time on 3G network)?This is realy important for me to know.I don't want my bill to be extra expensive.