Yes, multiple links from low PR (although PR6-7 is likely to be considered pretty strong for all but those with very high budgets) can achieve the same effects as one link from a high PR page.
Yes you can improve your ranking in SERPs with PR 6 pr 7 Links. Go for Article Submissions also to improve your ranking.
In my experience, if you are looking to improve your search rankings, as opposed to improving your page PR, then the relevancy of the sites linking to you is more important than their PR. Mark
Why not If you have relevant backlinks from PR5+ sites then it all counts specially in boosting your serp rank for particular keyword used in anchor.
I also don't have any backlink from PR5+ site and google judges my site one of the most relevant ones so you don't need high PR links, but relavant.
precisely! having a relevant backlinks with a PR 6 and 7 is matter especially when when boosting your serp. Continue gathering a quality and relevant site and keep on doing your one way link building..
Yes, relevancy is definitely the most important thing if you are looking for better search engine results. Of-course, if you are not worried about search engine results and are just trying to improve the PR of your page, then the PR of the pages linking to you is more important than relevancy. Mark