What are the advantages of using AdWords over other PPC search ?

One advantage for using Google AdWords over other PPC search
engines like Overture is that Google AdWords lets you setup a display URL and
destination URL in your AdWord. This enables you to use your affiliate links in
your Google AdWord. When someone clicks on your AdWord, they are sent to
the merchants web site with your affiliate id in it. If someone makes a purchase
you earn a commission. This is an advantage over Overture because it precludes
the need for a web site. Overture requires that you own the web site that you are
sending traffic to. Therefore, with Overture you cannot send traffic directly to your affiliate link. You have to build a web page first.

How to add n......... No of Keywords in your Adwords Account?

Now there is a way for you to do this. You could do this in your title:
Buy {KeyWord} here.
And you can also do it in your description:
We carry many {KeyWord}.
For example, if a user searched for "blue shoes" your AdWord would look like
this:
Buy blue shoes here.
We carry many blue shoes.
So, in the Google search results {keyword} would be replaced in your AdWords
listing with the keyword the user searched for, as long as it is in your keyword list.