My clients are really happy with adwords. They get many potential customers. Depends on the business though.
Yes, but adwords is a tough beast to tackle. Start learning some SEO for now until you learn the ropes. Then you can try some google content. But don't forget about msn and yahoo!
adwords is really worth it especially if your site is practically new and you wanted to get noticed early. Aside from that, it gives you targetted traffic.
i used adwords to push traffic to adult sites a few years ago and made nice money. then everyone started doing this and traffic became less and less productive and at the end became worthless. i guess you have to sell something really unique and exclusive to make money with adwords today