[aiharkness]

1 - When you turn off data services, you turn off data services.

Your BlackBerry accesses the voice "network" and the data "network" (leaving aside bluetooth device pairing). Data (internet and BlackBerry services) can be accessed through the mobile network or through a wifi connection. You can turn off mobile, or wifi, or both in manage connections. (When you turn of mobile, you turn off voice, too, unless you have UMA and wifi is on). When you turn off data services in option, you turn off ALL data.

2 - Generally speaking, if mobile network and wifi are enabled, the device will use wifi. If you have UMA (look it up) there will be a "preferred connection" option in which you can set wifi preferred. However, some user's have reported that the BlackBerry will sometimes "drop" some data onto the mobile network even when wifi is enabled. The only way to be sure all data goes through wifi is to disable mobile network.

3 - See #2.

Turn wifi on when you want to use it, or leave it on all the time and the device will switch to wifi automatically when you are in range of a saved wifi profile. If you wander into a hotspot zone, the BlackBerry will prompt you if wifi is on and you have set the BlackBerry to prompt you that it detects a hotspot.