Question about installing subs

[47_MasoN_47]

Alright I've replaced all the speakers and the deck in my '09 sedan. I generally listen to death metal so the Kappas I had in the back put out more bass than I needed anyway so I never worried with a sub. A friend of mine introduced me to dubstep and I enjoy it rather thoroughly. Problem is that without a sub it sounds weird in my car. Some songs are fine but some are so low I guess those speakers just can't put the sound out or something. Either way I'd like to clean it up (my deck has a hi-pass filter) and just dump all the bass to some subs. I've never done a sub install before, all the audio I've ever installed for people has just been decks and speaker swaps. Don't know the first thing about car subwoofer installs. I am under the impression that I basically have to have an amp to run one of these so I have a few questions.

1. I have the 10% underdrive pulley. Am I going to drain my battery with an amp if I'm listening to it loud down the road?

2. What are some good recommendations for use in the Yaris? I don't have to be heard a mile away, but I'd like to rattle mirrors around a bit :P