I'ld be glad if someone could tell me if:

1) I'll have some problems upgrading my italian firmware with the english one (it's the only language i've found)

2) The language will remain italian or will change into english.

Thanks...

The firmware will change the languages to whatever languages are in the firmware files you're going to use.

If you use Nokia Software Updater ( http://www.nokia.com/softwareupdate ), the phone will get the latest version of whatever firmware - and whatever languages it has - when it left the factory where it was made (assuming the product code has not been changed, that is).