Most serious vocal instructors I know would discourage putting her in formal voice lessons until she is 17. Her voice is developing. You do not want her to push it beyond its limits--she can develop permanent serious problems, like vocal nodes. People do it, but often do as much harm as good.
Putting her in piano lessons would probably be the wisest thing you could do. She will learn to read music, which will help her to develop her voice her own way, naturally. She will also develop an ear, which will help her down the road with harmonization, intonation, etc. Guitar is good, but doesn't offer the same sort of opportunities--I recommend it as a second instrument. (Besides, if she decides to pursue music in college, she will be required to take piano. That's not a funn thing when you're a college freshman...) Encourage her to be involved in school choirs, community theatre, church choirs, etc.
If you want to find a vocal instructor down the road, put in a call to the nearest college with a music program and they should be able to direct you to someone nearby.
Singin' Chicken--? Do you have anything to add to this?