Lord of the Rings, The Fellowship of the ring

Comments
1. Frodo, Sam, and Pippin are still on there way to Frodo's new home.
2. On the way There while walking down the road they encounter another black rider. They all quickly hide but the rider starts to sniff crawel torwards were Frodo is hideing then three eleves start coming down the road singing and the rider flees
3. Frodo and his friends talk to them and they are very cheerful. Frodo ask's to join them at first they refuse but then Frodo tells them of thr rider's and the eleves then turn very grim and asks him and his friend's to come with them.
4. The elevs led them to safety and one of the eleves warns frodo never to go near the rider because they are dangerous.
5. Frodo then finally arrives at his new house Where he tells his friends that he will be leaveing them to go to rivendale but they say to him that their going with him.
Questions
1. Who are the eleves?
2. Why do the rides sniff?
3. Why does Frodo leaveing a house he just bought?
4. What was the point of buying it when he's going to just leave it anyway>
Vocab
1. Enemy. Someone or something that is trying to hurt you or beat you in something, a rival.
2. Brew. a certain group of drink that was made in the same pot.
3. Fairy. A small boat that is usually found on lakes or rivers which takes people to the other side.
Literature terms
1&2 dramatic Irony. I'm putting both of mt Lit. terms together because their are two really good examples of dramatic Irony in the story. The first would be when frodo reveals that he is going to rivendall we know this but his friends don't. The second would be when Frodo tells the elves about the rider he knows it serious but they don't and he knows about the rider but they don't. The reader also knows which makes both cases dramatic irony.
Final Comment
It is really comgufseing what the riders are I still don't understand.