when you restore it to "Factory" it puts the latest firmware on your iphone and you cant put older firmware with out shsh blobs unless you use the iphone 3g..
and since she has no shsh blobs there is no way to downgrade
On the bright side... the 4.2.7 JB shouldn't be too far away so hang in there. greenpois0n are saying they have it working. I doubt it will be too long before they release it.
If you are going to JB. Make sure you avoid the "Upgrade" button when a new version of iOS comes out. Only upgrade after the JB has been released for the new version.
It will save you much hassle, and you won't dislike Unleashed for giving you the bad news
Not for respring. Only for reboot or if the phone is turned off. Also if you don't install things like SB settings, winterboard (anything from cydia that asks you to reboot to complete the install) the jailbreak will be untethered...