1.You can flash the Orange software onto th device, but you don't need to in order to use Orange -- as long as it's unlocked, it won't matter that it has the vodafone software on it. In any event, you can get the Orange Software here: https://www.blackberry.com/Downloads...223C61B1B5AB89
2. Simply putting in your Orange sim card will allow the Phone components of the device to be used. However, if you want to use the data components (web browsing, email, instant messagin), you're going to have to add blackberry data service to you plan.
3. Enterprise edition refers to a data plan which will operate with a Blackberry Enterprise Server ("BES"), either hosted by your company or by a third party hosting service. Blackberry data plans generally are more expensive if you want to use a BES. Using a BES allows you (1) to use the hosts internet connection, which may be faster than your provider, and (2) get push email through your host. However, the Blackberry Internet Service ("BIS") now provides for push email through some internet email sites (like gmail). If you're company doesn't have a BES, than it's likely you don't need to purchase the Enterprise data plan.