Noob Question About Page Rank

I recently found a long tail keyword that has no competition at all. My question is what do I really need to become to on top?

To have exact keywords would me make me on top?
Do I need have to purchase a domain that exact match with the keyword?
I have a domain already but its general only one word match with keyword.
Do I need to submit articles, backlinking, social bookmarking and forum posting?

What is the best CPA that pays via paypal? Thanks.

If there is really NO competition then all you need is to get the page indexed and include the long tail keyword somewhere in its content. One run of Stat Blaster will do the job.

It states it in google adwords keyword tool that it has no competition. Is this really reliable?

If your talking about the 'Competition' coloumn, thats the number of Adword advertisers bidding on each keyword, not actually how competitive the market is in SEO terms.

Ignore that coloumn, thats just for adwords. (although obviously gives you a slight idea how popular a keyword is)

The only way a keyword has no competition is if there are no results for the keyword in google! Very literal in this sense, ha.