What is the right way to write and submit articles?

Since I started my PIPS Web page I've waded the net for a huge amount of information related to marketing for the web. I recognized early that one of the most effective strategies is the marketing of niche related articles and I have crawled a lot to find stuff about this topic. But there are many different opinions out there of what is really the best solution. Therefore I'd like to know what is the best experience and practices from the members of the warrior forum.

Here is some questions I've made related to this subject and I'm sure someone inside here can give me and other members valuable tips and recommendations.

Let's say that I have decided for a particular niche and a suitable product. Then I started to write some articles that are optimized for related search. The first step is to add the first unique article on ezinearticles.com, and the next is to submit the same article to several other directories.

1) Shall I rewrite the article so it not will be a duplicate of the first one? If I put the same unique article on another article directory, can that duplicate destroy the effect in ezinearticles?

2) If I should rewrite the article for another directory, how much in percent do I have to rewrite it?

3) If I decide to put the article in 25 directories, shall I rewrite 25 times? If I have 1 article, that means 25 rewritten articles and 3 articles means 75. That is really a lot of of work. If I optimize them for the search engines too, that makes it a tremendous amount of work.

4) Can I use an article spinner to do the job? I read from some experts out there that is not good to use such software/services because the article itself will lose some effect and be hurted instead. Is that right?

4) For the effect of submitting articles, how many article directories is it recommended that I submit to?

5) Can I have those articles on my website too, for example my blog? And do I have to rewrite in this case too?

Appreciate your answers!

Ragnhild