Let me tell you how I wish my mom had handled these things. I am a very private person, I didn't want her knowing when or why I was shaving my legs. My mom was always violating my privacy and assuming things about me that weren't true (like if I was shaving it was because I felt bad about having hair or was getting with boys. Both false). This drove me to such a level of secrecy that she didn't even know I had gotten my period until two years after the fact.... Some kids won't ask their parents, they just want to handle it themselves.
Just let your daughter know that if she wants to shave her legs, there are razors and creme available in the cabinet. Tell her to rinse her razor and dry it after use so it doesn't become dull.
Don't ask her if she wants to shave, don't bother getting into why some people shave and others don't, just let her know it's available if she wants to. Learn more about the myths of shaving so that you can help her be better informed. Shaving is not capable of changing the way hair grows in (aside from ingrown hairs of course) or it's color, texture etc.
Shaving has to be hygenic, so be sure to talk with her sometimes about when people get ingrown hairs etc and how that is handled.
Keep Nair out of your house, that stuff is not very safe, especially for young people http://www.livestrong.com/article/80270-dangers-nair-hair-removal/
If she wants to wax at some point, I have always liked Nads. It's easy to use and kind of fun lol, she can do it herself no problem.
You can use a cheap beard trimmer to clip leg hair short, I do this so I'm not damaging my skin from too much shaving, but I wouldn't recommend it for a young person. The clippers are always loud and everyone else in the house will know what she's doing which some kids don't appreciate. Plus when she's got pubic hair if she goes after it with electric clippers she's going to maim herself. Catching a labia in those things is really painful :/