For now I have a baptism/Holy Ghost talk for you.
You will need:
~Mason jar (any jar will work, but about that size)
~Dirt (enough to fill the jar)
~a Scooper for the dirt (the ones that come with baby formula, drink mixes, etc work great)
Now for the talk....
Hold up the jar and explain that this represents the person who was just baptized. Hold up the quarter and explain that it represents the Holy Ghost and drop it in the jar and shake it. Ask the kids if they can hear the Holy Ghost. Add a scoop of dirt, while doing so give a scenario of some wrong doing (for ideas see below). Shake the jar again and ask if they can still hear the Holy Ghost. (which they should) Continue adding scoops, giving scenarios, and shaking the jar, and soon they will no longer be able to hear the Holy Ghost.
When we sin, the Holy Ghost withdraws from us and can't speak with us. Then ask the kids, how we can hear the Holy Ghost again, then talk about repentance and the atonement. And dump the dirt into the bowl and put the quarter back in. Explain that the jar is still dirty because even though Heavenly Father has forgiven us, we will still to able to remember the mistakes we make so that we don't do them again. As a little gift for the kiddo getting baptize you could have a different jar already made half filled with dirt (shake it around so that the top half is dirty), put a quarter on top of the dirt, then seal it with hot glue so that you can keep the mom's sanity and dirt isn't found around her house, haha. Then on the jar you could put this cute little handout.