The term SEO as we know it is very vague. If one thought that just putting a few keywords at random throughout the text is enough, let me remind you that it is wrong. Search engine algorithms have changed drastically. Nowadays one needs to pepper the text with 2nd tier and 3rd tier words too. Just a small example. If your main keyword was shoes, you need to sprinkle words like leather and footwear too.
Researching and analyzing a good set of primary, secondary and tertiary keywords takes about 36-72 hours, assuming that just one product is going to be used.
Page rank is the measure of a website's popularity. It is the tool devised by google team to specify the popularity of a website on the basis of ranking system on the scale of 1 to 10. Thus, rank 1 means less popular website and 10 for most popular one.If you wnat to access the page rank of each website visited by you, you need to install google toolbar, which also include page rank bar.
Here is a helpful link for installing and customizing google toolbar.