yes, these topics should be covered with newbies and even experienced boaters alike. just last w/e, i was with someone on grizzly who put himself at a high risk of foot entrapment. this is a guy i have boated with before, and is well beyond newbie state. he swam (after attempting to roll 2 or 3 times), and quickly tried to stand up in waist deep water while holding his boat downstream of him. the water appeared to be slow, but it was plenty strong enough to hold him if his foot became entrapped due to the added pull of his boat. he let go of his boat rather quickly after my verbal lashing, but still "walked" to shore.
i can't remember the exact saying, but i heard something along the lines of "don't try to stand in moving water over ankle deep" in some safety class i took. a good thing to tell your newbie and beginner friends.