My daughter is on our plan and she has talk and text only. She has a basic LG non-SIM card phone. She recently received an iPhone 4s and I understand that I can switch her over to that phone easily through iTunes. Would I incur additional cost? She would use the iPhone for talk and text only, but would like to access data through wifi.
You can't activate it as a phone without a SIM card, which requires a data plan. You can limit the plan, or even turn data off on the account, but it requires data.
itunes has nothing to do with your phone service. It can't be used to convert he service to the new phone.
itunes is for adding music, games and utilities to the phone. The iPhone is a very advanced PDO ( private data organizer)