I would imagine that your neighbor would not be interested in friends with benefits. I could be wrong.
I would also imagine that a 23 year old would not want to date someone twice her age. It has happened before, but it's probably not likely that she will fall for you.
Having said that, it's a free country and if you want to try to woo her go for it. You need to be able to hang out with her, socialize, flirt with her, touch her appropriately. etc.