Of course, the age of the domain is an important factor. The older the domain, the better SEO it gets. I have not heard much about H1, H2 and H3 tags. I think they are not very important for high search engine listing results. Some people replied saying these H tags are just speculation. Yeah, it's hard to know how Google looks at these kinds of things.
I wasn't completely sure about what Link Juice means. I found out after I went to this web site:
http://thekeywordacademy.com/link-juice-explained. It's all about creating better links to be compete with your competitors. Google maps out link relationships on an enormous scale and that’s what makes them Google.
SEO experts will look at Google information and understand more. I think beginners are having a hard time trying to understand what Google is looking for.