Search Engine Optimization

[Thomas]

Hi friends,

I am new to SEO concept and looking for some help from you all, I have a few questions which are running in my mind regarding SEO.

1) How can I come to know that for which google TLD I will have to do SEO? As there are many TLD for google such as .com, .co.uk, .co.jp and so on.
2) How can I justify that whether the SEO I am doing is increasing my Site Rank on all Google TLD's?
3) What is a Page Rank? Is this the same think as Ranking in Google Website?
4) If it is something different then is it also a part of SEO?