Backing up/Restoring for Carrier Unlock

[prongs]

Hey,

After a bit of help!
Ive got a 3GS Jailbroken at 4.1 with limerain, Cydia has the SHSH blobs 4.0, 4.0.1, 4.0.2, 4.1, 4.2.1+, 4.3 (Not quite sure how I have them before 4.1)
I need my phone unlocked for when im away, so I have requested a Carrier unlock. I read that I will have to do a full restore for this to work?
How can I back up all my apps at the moment? They are currently synced with itunes using appsync... Do I have to do something more?
Will I need to download FW4.1 and do the trick with the SHSH blob after restore? Then rejailbreak with limerain again?

Can anyone point me to guides on this? The ones I have found seem out of date...

Would I be better off using ultrasnow? My baseband is 05.14.02... I dont know if it is a bad idea to do it this way?

Thanks for your help!

 

[prongs]

I guess my main question is at which point during a restore does the unlocked signal from apple come? If the restore will try and upgrade me to 4.3 and I have to choose my own fw file, pointing to cydia servers will the unlock still get through?