Yahoo Optimization - How good it is ?

My Questions

1) Is optimizing a site for yahoo has any advantage ? I mean does a site good enough traffic ?

2) Is optimizing for yahoo & google can be done at same time. I mean there are no techniques for optimization that is considered good in 1 search engine & bad in another.

3) Does backlinks has a role in improving ranking in Yahoo ?

4) What are the main factors that improve ranking in Yahoo ?

1) Yes.

2) Optimizing for Google will simultaneously optimize your site for Yahoo too.

3) Yes, it does. Backlinks count in almost all the major search engines.

4) Similar to Google though many are unknown to the normal man.