Is it possible for someone to fake being under hypnosis?  If so, is it very common?
Sure, it is possible.  I haven't seen this except in kids acting silly.

I suppose someone who is only mildly susceptible to imaginative suggestions could really want to please the hypnotist, or to make points with the group around them, and pretend to be deeper in hypnosis than they really are.  The person probably wouldn't get the benefits like pain reduction or inner attitude changes by faking it.  What would be the motivation for faking it? 

I always have a dream about children in different situations.  What could that indicate?
Without knowing more about the specific individual dreams, it's hard to say.  In my dreams, children (especially babies) have often represented my creative projects underway.  Sometimes they represent my responsibilities in life.  Sometimes they represent my innocence or curiosity, depending on what they are doing, what mood they are in, etc.  When you have a dream about a child or children, look for the details in the dream to give you clues about what part of yourself is being represented by the child, and what the message from yourself to yourself might be.

How can I start making better sleep habits?  I seem to always wake up two to three times throughout the night.  
One question is, do you go right back to sleep?  If so, no big deal.  Sometimes when you stop worrying about waking up, you stop waking up.

Other possibilities to check:

• Drinking fluids in the evening can mean full bladder signals waking you up in the night.  Cut out liquids after dinner and see if that helps.  Especially avoid caffeine after noon.  
• Are you waking up with dreams in mind?  If so, try writing them down immediately and then analyze them the  next morning.  Perhaps your unconscious mind is trying to give you a message.  Pay attention.  "Honor the dream."  Often, when this happens to me, once the dream is scribbled in my notebook, I can slip right back into sleep -- sometimes  into a continuation of the same dream.
• Are you going to bed with worries or long to do lists in your head?  Or are you generally stressed out? Physically writing down your lists of chores, shopping items and agenda for the next few days can help you relax for the night.  Once these things are written, they are where you will safely see and remember them.  If you make a habit of checking your lists and completing those items, your unconscious mind won't need to keep waking you up to remind you of things!  Completing your tasks will also help you reduce stress levels and feel more at peace on a daily basis.
• The usual list for good sleep habits includes keeping your room nice and dark, not allowing pets in your bed, using a fan or CD for "white noise", keeping the room cool, and only using your bed for sleep or sex.  Go to sleep and get up at the same times every day.
• If you do wake up and have difficulty going back to sleep, experts suggest getting up and doing something quiet for a while until you are sleepy again.  For instance, read your boring textbook!

I hope these ideas are helpful.  Thanks for asking!