Only if you want to be able to access the internet with it. If you don't plan on doing that at all or only limited data usage, you don't need a data plan.
Before you can use internet on an Blackberry phones, you would need to register the device for the special Blackberry Data plan. Any regular data plan would not work on Blackberry phones.
Metro pcs
It depends on the phone and the carrier. Some sell unlocked phones, other sell locked phones but you can ask them to unlock it. Others are not locked per-se but may be blocked from being used on certain networks. (In the US, for example, prepaid Verizon phones cannot be used on Page Plus.)
Most phones do not require a data plan. But with Samsung, I have always had great service without the data plan, and i dont believe you need the plan for the phone to be great.
The data plan is usually reserved for smart phones. Most companies offer a unlimited web usage, and email with most phones for about 25 dollars a month.
Blackberry and the carriers require you have a data plan for all Blackberry phones.
Yes, it will be unlocked and the data plan will be month to month. No contract.
Unlocked phones are phones that you can buy that are not permanently connected to any phone company. You can get a cell phone plan from any company that you desire after you own the hardware. If you are going to be traveling, it is a good idea to get unlocked phones. This will allow you to put them on a plan with the main provider in the country that you end up in, which may be different than the main provider at home.
If the Blackberry 8800 is already unlocked, then yes, you should be able to use the phone on the Orange carrier. If you want to use the Blackberry data service, then you would need to register the device for a Blackberry Data plan as regular data plans do not work on Blackberry phones.
To use internet on Sidekick phones, you would need to register the device for a Sidekick Data plan, as regular data plans do not work on these phones.
Flipout is available from At&T, but they do need a data plan. This is an older phone you may want to go with a newer phone for support reasons. You can find unlocked phones but I found no support for other carriers for these.
Since i just replaced mine i can truthfully answer this yes you would unless its a different type of phone meaning smartphone, messaging phones, data phones like if you get a data phone you will need to get the data plan since those phones require internet. But if you get a phone within the same jurisdiction you should have the same plan.