Where do you find the MAC address on a smartphone?

In order to access Hotspot provided by your internet provider you may have to register your phones with the service provider. You will also require your userid and password. The provider would ask for the MAC (Machine Access Control) address of your phone. MAC address is also called Physical Address. Normally this is found in the settings of your phone.

For Windows Phone Microsoft Lumia 950 it is found under:
Settings---About---Device Information--MAC ADDRESS
With the following format:
Mac Address: 33-F3-8D-99-0A-99 (some fictitious address)

For Apple iPhone 6S it is found under:
Settings-----General----About---;Wi-Fi address
with the format similar to the above.
Wi-Fi address: 33:F3:8D:99:0A:99 (some fictitious address)

You better don't give away your MAC address to anybody as it is unique for a phone. If somebody spoofs it and commits something inappropriate you could be blamed for it.

What is MirrorLink protocol?

MirrorLink Protocol which is presently in version 1.1 allows third-party apps to on board screens in automobiles. It is an interoperability standard to interface smartphones with the car's in vehicle infotainment (IVI) system.  This allows drivers to access more mobile apps from dashboards. This may not be as distracting as you think it will be, due to the fact that there are resrictions on how it is implemented. The Car Connectivity Consortium (CCC) is behind MirrorLink.

Apps should follow CCC guidelines to get their apps on dashboards. App developers would need the CCC approval which defines two categories, base category and drive category. The drive category apps will be those that can be used while the car in motion.

Here are some MirrorLink enabled displays taken from this site.