msafi - 12:13 am on Nov 2, 2008 (gmt 0)

I wrote an article and immediately after being indexed it ranked on page 1. Now it is #3 on page 1. It brings me about 50 visitors per day and it's about 700 words. I know the keywords that I wanted to target when I wrote the article, but I didn't expect it to rank so high so fast for those keywords. Honestly, I just lucked out. Now, I would really love to know:

How can I find more keywords like this?
How can I predict where a page will rank on SERPs once it's published?
How can I determine how tough the competition for the keyword is?

Thanks a lot,