DIY. painting crib a different color tips?

my mother bought me a crib at a garage sale she got it for a good deal I originally wanted a grey one and she got me like a yellow brown color one I let her know I appreciate the crib because I do but I want to change the color. she is ok with that but how do I go about doing it

1. do I have to take the yellow color off by sanding or putting paint thinner on it or can I just paint it over with grey paint?

2. my last child bit the crib rails and of her crib and left bite marks all over what kind of paint can I use that is not toxic? I don't know if this one will chew on his crib? what are the kinds of paint for this project I don't want peeling paint either I think latex peels? right?

3. do I have to buy a top coat or primer like with nail polish??

I am scared of messing up please any tips would help.

I would post a picture but it's at my moms attic since baby won't be here til November

thanks in advance!