Search Engine Forums, SEO Forum

Yes, those are a smaller factor in ranking in SERP, apart from that, Content, onsite setup, quality backlinks are the key to success in SERP.

I don't think they have a bearing on SERPs, however those with extension names such as .edu, .gov, etc have more weight when it comes to measuring backlinks for Google sees them as reliable and more valid for link exchanges

Although domain extensions might factor in SERP ranking, this is very minimal at best. What factors more in SERP rankings are quality content and backlinks. So, even if you have dot com as your domain extension, you will still have a great chance of getting yourself on the top SERP rankings if you provide fresh, informative, useful and unique content always and has highly credible and authoritative links leading back to your site.