If I purchase a domain that was about to expire, say PR6, and it was previously about cooking, and all its backlinks are related to cooking...I purchase this domain, then I change the onsite content and onsite seo to furniture...will that PR be lost? Or will I still have all those backlinks helping the sites new PR campaign? Need a real guru to help me , plz answer anything you feel would help out besides what I asked as well...I appreciate it as always.
pr will not be lost but you will not rank with furniture related keywords. if you want to rank furniture related keywords , you must start building backlinks with furniture related anchor text
Pagerank has nothing to do with the content, however you run the risk of the cooking webmasters seeing it's changed to furniture and removing the links.
Totally irrelevant backlinks may be devalued eventually. You may keep the current PR but can lose it later. Don't expect for a good position in the SERP unless you re-build backlinks. I think it's much better to re-build similar content, keeping the same niche.