yes, it helps to SERP.
Yes alexa rating gets calculated by alexa toolbar.
I agree with hem1234, .info's they don't discriminate.
3 way link exchanges are not penalized, and if those links are quality and relevant then more effective to you.
PR based on quality of back links, you can build quality links from blog comments, link exchange, article posting, forums posting.
Yes, it's working good.
You can do post articles, those are most effective for traffic.
This interest fact, with PR.
I think no difference there.
simply you can do 301 redirect.
I continue to using the directory submissions as long as the directory provides a good quality link.
My suggestion is using the image description on alt tag.
Both are important on SEO, you can use right meta and do promote your site.
You can you link exchange with relevant and high pr sites.
I think all tools are not given accurate results.
Separate names with a comma.