Well normally .com domain is the most powerful domain extension for SEO. If that is available for the URL name you are looking for then indeed go for it.
Depends on the domain as well, for example if I had technology.info it could turn out to be a very good domain if I am going to have information or a blog perhaps on technology. I think it just depends on the usage.
I don't think .com .org .net and .info has any preference by search engine for SEO. As long as it is a TLD, it is good for SEO. And another factor is the content and the quality of it in the domain.
Just as long as the domain does not contain malicious content and etc., it will be doing just fine.
Yes, it can be effective. Domain extension doesn't matter if you have rich Organic content with proper backlinks towards your site. If you are following White-hat SEO methods and doing continuous SEO, SMO work than .info domain can meet your goal of success.