is it normal to keep changing keywords n't first one ,from second key to the last one ,change place adding removing? for new page rank how long it take for new site to have page rank? how changing keywords effect pr?
changing key words doesnt efect your page rank just your number of pages and pages that link to you effects your rank.
keywords only matter, at showing your pages at SERP. Pr is about content value on your page and backlinks.
SERPs do change depending on your competitors link building or content change. However, it does not influence your PR.