Yeah, helis require constant input to keep them stable. Its like balancing a bowling ball on a pencil when you are first learning. As you get better, its more like balancing a pingpong ball on a pencil. You will always have to "fly" the heli, but it becomes easier the more you do it.

As far as tail fins go. There are a few of reasons for them.

1. In fast forward flight the fins act like a weathervane, and keep the tail straight.
2. It makes the tail easier to see.
3. It looks cool.