3g!! damn!!!been long time lol!!
i think if you want to know the baseband and other stuffs you can download "tinyumbrella" and it will show the info u need
i dont really think u need to know the baseband..
put ur iphone in DFU mode!!  
and download blackra1n or greenpoison or absinthe..
they dont require you to select the ipsw..
its just plug in ur iphone ...put ur phone in dfu mode and then click jailbreak

i would just go and try and see what happens !!
good luck