Only you can tell whether that is ok for you or not. You can use that if you find good result. no problem with that.
If you are also using Mozilla firefox, just add the SEO plugin, it will give you the PR, the backlinks of major search engine sites.
Go to Yahoo.com and click inside the search bar. In the search bar you need to type in site:www.yourdomainname.com, replacing the sample domain name with your own of course. Then hit enter or click on "Web Search". This will take you to a page in Yahoo! called the Yahoo! Search Site Explorer.
yes. it is right. To get all the baclink pointed to your domain active webmaster on your domain. Now webmaster tool has function in which you can find all the backlinks.
I don't have any idea how to check backlinks in Yahoo but for the index pages in very SE i have an idea what to do.