Yes. IMessage is not the same as the text messaging you have in something like a Samsung phone. iMessage only works with other Apple devices that have iMessage.
If you have iMessage installed you can only iMessage other iDevices that has iMessage installed on them. If someone has an iPad 2 but not with 3G but has an iPhone, then the iMessage will go there iPhone.
If you have or can install the iMessage software on it you can but if not you can't. You can only iMessage other iDevices.
Now u can, with iMessage.
It is blue
Yes, it is
If your phone does not revert to SMS and the receiver also has imessage there will be no data charges. The apple server controls imessage in this case.
You use iMessage which is available on the latest iOS upgrade. iMessage operates via wifi, so you must be in reach of a wifi network in order for your iMessage to be sent.
Yes. iMessage
Pinger, text free, and text plus are all good apps.
Find a place with a wi-fi signal, then use the iMessage app, or TextPlus, to text whoever you choose
Apple's iMessage allows senders to confirm that a text message has been delivered, this service is only available on Apple's devices and to work fully both user and sender must be using wifi otherwise the iMessage is sent as a text message. iMessage is a free service (unless message has been sent as a text).