There is a script that tries to do automounting of all removable storage hence why /dev/mmcblk0p* shows up. We boot from mmc so yes, this device is exactly what '/' is. There is no issue in mounting a device multiple times in linux. If you look at meta-intel-iot-devkit/meta-iot-devkit/recipes-core/initscripts/initscripts-1.0/ you will see exactly the scripts and what they do to do this automount stuff. On your board /etc/mdev.conf controls what gets automounted.
/dev/mmcblk0p2 on / type ext3 /dev/mmcblk0p1 on /media/mmcblk0p1 type vfat (rw,relatime,sync,fmask=0000,dmask=0000,allow_utime=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro) /dev/mmcblk0p2 on /media/mmcblk0p2 type ext3 (rw,relatime,errors=continue,user_xattr,acl,barrier=1,data=writeback) none on /dev/mqueue type mqueue (rw,relatime)
Mounting /boot is not required in linux, however to reduce confusion future images should do this, it's a bit more 'typical'.