craftgrrl | Painting a keepsake box

Hey everyone,
For my and my boyfriend's four year anniversary I am making him a present. I have a wooden keepsake box from Joanns (like this) and I want to paint it, and on the top I am going to write the word "love" in different languages, and along the sides or maybe inside I'm going to write song lyrics from songs that are meaningful to us, and then maybe some other designs or pictures of us on the inside or the sides. So my first question is, I was planning on painting the box with some paint that I already have which I bought from a ceramic store and also like silver gel pens to write on it. Will this work? I've never used the paint on anything other than ceramics, but it seems like it would be okay, but I'm not sure. Also, the box is "unfinished", so will the paint look okay if I just paint it directly on without anything underneath it? And further, do I need to do anything after I paint it to seal it or can I just leave it? And just any general advice or more ideas anyone may have would be welcome! Thanks so much!
Amy