You can check your rank by searching for a certain keyword in yahoo and see if what your rank for that key word is. To rank high in yahoo you need back links with relevant anchor text
do you mean page rank or the result ranking, if you are talking about pagerank it would only affect google
You might be interested to read this post Your Success with Yahoo Search Engine - Drive Traffic It might help you to perform better on Yahoo!
To improve your yahoo ranking at particular keywords, you have to make some good link with right anchor text............
Anchor text and backlinks are both really important in the battle to reach the top of Yahoo in our experience. Google is easier to conquer!
It is easier to rank higher in yahoo for competitive keywords than it is in google. To improve your ranking in the serps you should build high quality backlinks.
Yahoo favors your site if you do a better interlinking between all your pages along with sufficient backlinks...
The best way to rank consistently on all search engines is by "optimizing in the frame of SEO"; Web 2.0 Optimization Services which focuses utlizing web 2.0 technologies such as blogs and RSS to bolster your websites overall SEO ranking. You can read my blog post on these techniques: "Next Generation SEO"