Page rank is an algorithm based off links, a page rank on a website will only increase or reduce in conjunction with the quality and quantity of incoming links.

No! Absolutely no!

The higher the Page Rank is, the more better it is, so the site with the highest Page Rank has the best Page Rank.

Its good to pay dor ads on terms that you already on for natural as it will increase your page rank

Page Rank assigned to blog by Google according to its page ranking system is called Blog Page Rank.

You can know it through Google toolbar.