V.P.
My 10 year old started about 5 months ago, and we're just now getting the hang of things. The biggest obstacle we've faced is finding a comfortable pad for her. The first month was fine, then the second month she decided that they weren't comfortable so she'd just wear 3 pairs of underwear instead - UGH! I discovered this when I was doing laundry! So we had a long talk, and have experimented with different pads. All of the thicker pads are too wide for the pelvic area of a 10 year old, and the narrower "pads" are all too thin (basically, they're just the liners). I really wish they still made the mini-pads with wings, but I haven't been able to find them anywhere. And she has no interest in tampons.
In terms of her classmates, no one knows, and there's not really a reason to tell them. She hasn't had any issues with embarrassment with the kids.