Articles won't help you much. I didn't think anyone bothered with articles anymore Even G directories are better than article spamming..... But if you really want to know how to beat all, then get something viral designed and use that instead.
it really depends on what your targeting. if you want to be in the top spot then you need tons of articles to make it.
Really depends on how competitive your keywords are - you may want to use other marketing methods to achieve better results.
if you write everytime a unique article and don't submit one article to many directories, then it will be more effective...
Normally if you submit to around 1000 directories, you will get around 400 approved, and these 400 links will give you an increase of pr with 1 -3.
Article submitting will help with both traffic and SERPs, but think more about the quality of the articles than than the quantity. One well written and interesting article will go much farther than ten poorly written ones.