iPhone updating iphone

[meanie]

got iphone 3g had for about 6 months i jail broke it
now if i do the update (i want to be able to picture message)
will i loose all the apps i put on there ?
can i jail break it again ?
any other things i need to be aware of ?

also looking to get a 3gs
does it act as a sat nav?
i take it if i jail break it if bat dies i have to jail break again ?
do i have to reinstall the apps too ?

 

[GTO]

yes update then re jailbrake with blackrain. you will probably have to re upload the apps(not sure).

the 3G and 3GS both have sat nav capabilities with tom tom or other software.


3GS as far as i know if the batt dies yes it will have to be re jailbroken as it is tethered.