Have a week 28 iphone, which is unlocked to work as a phone but I dont know how exactly it was done. It is definitely not by AnySIM or any other software solution. It is a hardware solution since the phone works from a non-original sim card (silver with an alpha sign on it, it is helps

the phone was never upgraded or downgraded. But is was Jailbroken by an early ibrickr version (i think version 0.8).

Now my aim is to get an upgrade coz the 1.0 version crashes frequently and "lags" after 3-4 days usage.

a) To what version should i upgrade to have a nice and stable system?
b) Does my boatloader gets upgraded, coz from what i gathered it is nicer to have an old version of it, as i do.
c) Do i need to virginize or not. I dont wanna get a brick. (P.S. if yes, help me out with a link to a nice guide ... i couldnt find any guides for 1.0 version)
d) Is virginizing required at all after a jailbreak?
e) What should be my next steps for to upgrade my phone. (Dont need full scale details, just nice and short right in the face - bulletpoints.)

Please, give some hints on that.

Thanks in advance

P.S. if it helps modem firmware 03.12.06_G