With regard to the potty training thing, I used the "naked and $60" method. Basically, I picked a long weekend when we didn't have to go anywhere or do anything, and stripped the child from the waist down (this is the perfect time of year to do it since it's warm). I had a little potty chair, but some kids prefer to use the "big" potty. I explained to the child that they were going to use the potty now, no more diapers! Then (and this is the important part) watch the child like a hawk! When you think maybe they might have to go, run to the potty with them and sit them down on it. You might have some false alarms, and the child may have some accidents. If they do have an accident, clean it up without making a fuss over it, and tell them, "Next time you'll make it to the potty." (I think they don't really know what it feels like to go potty when they wear diapers - so being naked from the waist down is actually very enlightening for them - they can SEE what happens, and what it feels like.) And then continue to watch carefully to make sure you get them to the potty in time the next time. The $60 is for carpet cleaning when you finally do get them potty trained. =) This process took me about 4 hours with my oldest (she was 23 months) and about 2 days with my youngest (she was 29 months). I didn't bother with charts because at that age, they don't really get it. And I figure, I don't reward them for eating with a fork, or putting their shoes on. It's just another life skill, and that's how I approached it. I hope that helps!
As far as the bath crayons, try a Mr. Clean magic eraser. I've had some luck with removing all kinds of things with those!