Questions re embedding MMC/SD (and digital cameras)

Hi all,

Quick question: I am only briefly familiar with MMC and SD, but my
understanding is that SD is a superset of MMC, and it is possible to
use SD cards as unprotected MMC devices without needing to acquire the
full SD spec. Is this true? So, can I use an SD card connector, only
use the MMC pins of it, and successfully read/write unencrypted
content on the device?

Related question: Do digital cameras, in general, use the SD
protection features, or can I read camera-formatted cards using the
MMC-only interface above?