iOS MMORPG game virtual goods rental purchase

[shouo713]

Hello everyone

i have some questions about the purchase want to ask. If anyone know please help me thanks a lot.

1.If a free application that has not been utilize any billing system, would
it be possible to modify to utilize the billing system during the service?

2.We are planning to release the application without the virtual goods in the
beginning. However, we will be selling our virtual goods after our
application is released.
Would it be possible to apply the (in app purchase) from the beginning
even-though we don’t have any virtual goods for sell?

3.Would it be possible to use the Rental Model to sell the items in the iOS game?(EXP: player can choose 7days 14days or 30days, and after that the item will expire.)

thanks again~