Hello, first of all, 
to ld4all!
Now, about RC’s. You said it yourself; you can’t easily realize you’re dreaming when you are, while you can easily realize reality when your awake. The whole point of doing RC’s IRL, is that those actions are carried over to the dreamworld. By doing RC’s when your awake, be it at random times of the day, or when something dreamlike happens, or whenever you see or do something- for example whenever you walk through a door- you eventually would be doing RC’s in your dream, randomly, or when something seems “not right” in the dream, or whenever you walk through a door in the dream. And when you do, you realize your dreaming and your lucid. By making RC’s a habit in daily life, that habit will eventually be carried forward to your dreams.
That’s what most believe, but sometimes, when you think you have woken up, it turns out to be a FA. And what’s a surefire way to find out? RC’s!
If you haven’t already, read thisBIG reality check topic.
Now, about Shared Dreams, i can’t say that it has happened to me, not that i know of anyhow. But, there are a few members that have had a Shared Dream, hopefully they can post their experiences. In the Beyond Dreaming forums, there are alot of discussions on Shared Dreams, look at the BIG shared dreams topic.
Hope this helped 