Kompilator @ 08/26/2011, 11:54 PM
2.3. How to install "jailbreak" to use "not signed" software?
Only if you manage to buy a smartphone with WP 7004 version.
Kompilator @ 08/26/2011, 11:54 PM
2. What is the situation with the firmware / firmware upgrade?
There is simply no firmware for this device. No. Only updates.
Kompilator @ 08/26/2011, 11:54 PM
2.1. Is there a big chance to kill him?
Only if you pull the cable during the upgrade.
Kompilator @ 08/26/2011, 11:54 PM
2.2. Is it possible to make a normal back-up
When any update is automatically made backup. The task is not to lose it, because there are no firmware.