Hopefully the info and the attached link info is relevant to your vehicle. It is for the Ford Navigation Sync System but the guide keeps stating if equipped, so I'm hoping that yours is.
Turning the text message notification on/off
You can choose to turn SYNC’s text message notification on or off.
1. Press the PHONE hard button.
2. Select the ‘Settings’ tab on the touchscreen.
3. Select ‘Advanced’.
4. Select ‘Txt Msg Notification’ and turn the feature on or off.
Select ‘On’ to turn text message notification on. With notifications turned on, an audible tone sounds during an incoming text message and response options appear in the display (i.e., view the message, have the system read the message aloud, dial the person sending the message or cancel).
Select ‘Off’ to turn text notifications off. With notifications turned off, you will not be notified by a tone and the incoming text message will not appear on screen.
Here is a link to the Sync Navigation System which may be applicable to your vehicle. Scroll to p.154 for text info. The other option you requested is shown further down the guide.