> Is there anything in particular that will cause the the death of the sun?

We expect it to start running out Hydrogen fuel. that would be the end of the current stage of the Sun's life, although it would continue on in other forms.

> What would happen if a small black hole collided with the sun?

I suppose it would depend on how big the hole was

> Do you think we could ever travel to the sun?

Well, the closest we will get in the near future is Solar Probe. See http://solarprobe.jhuapl.edu/mission/index.php