Well, I’ve never had an LD yet, hoping to try more in the summer. A year of not having one has got me really wanting one 
Anyways, I was wondering about DC’s. They seem interesting. People have said they are personifications of your subconcience (Ya, I don’t know how to spell it <_<). Is this true? If I had a lucid dream, I’d really like to talk to myself, and this seems like it’d be a good way.
Would you then be able to ask them to do things for you? Say you needed to remember something for a test. Could you ask one to remember it, and then when you wake up it will be stuck in your head?
Also, I’ve been wondering if people have ever injured a DC? I want to make sure there are no negative effects to this before I one day have a LD. I wouldn’t want to set one on fire, and then wake up as a vegetable 
I can’t answer your test question, but you can mess up DC’s any way you want!
As a whole, they are your subconcious, but harming one of them wont hurt your SC they don’t form your SC. They are only representations of a (small) part of it.
If you want to ask them questions, they can give you some insightful answers about yourself like what you want the most, etc.
Do not ask them questions about the future or something like that, they can’t possibly know something like that as they are part of your mind.
I am reluctant to call DC’s representations of the subconscious. They are projections! Not a specific thing, just, an image. However. Your subconscious is always listening. Awake or dreaming. The advantage of the dream is that the subconscious can answer, through anything in the dream. a person, a note, a sound, a feeling. But it may be more tricky than it sounds. You can’t really tell if your answer is from your subconscious or your conscious expectation. Never the less, you can probably find out lots of meaningful things, if you listen.