Does this lead allow you to control the iphone via its controls., Currently with the lead i have my phone displays accessory connected
You will require the MDI box too. But to answer your question,
If you have full MFD2/3 FIS display then you will be able to access the playlist, music etc. from the display with steering wheel controls.
Otherwise from the rcd310. It works surprisingly well.
You will need to upgrade to the latest firmware on the MDI, otherwise you might loose a couple of seconds from the begin of songs or the song name that does not always update.