Well the crops, the dispenser is not blocked, but set up so that the bone will go on top of the crops in order to have them grow. It's a very common farm design and I have even used it before in other worlds and the world I am currently playing. But it has stopped working, and I can't be sure for how long as it's not a farm I use often.
Tilled soil generally with carrots planted, as I am using the bone meal to grow them, I've also tried it in front of a grass block to grow flowers.
Yes