I can't find a reliable answer anywhere...
I know Ipads do!
Yes, all Internet capable devices have mac addresses
all NIC's are given them upon manufacturing. The Internet (and cellular communication) wouldn't work without them
Yes, you should be able to find the Mac Address of your phone pretty easily.
I have a pretty locked down Network at home, when someone wants to use my network, I have to take a peak at their phone first, pull off the Mac Address and add it into the "Allowed" list of users.
No, only Apple products have Mac addresses, hence the name.
As said all network devices should have them!
My Android phone does