Web 2.0's can still work. But you have to cautious about constantly linking between the two same sites, that can have a very negative on your SEO and Google can tell that those are not natural links and could possibly penalize you.
High rated as in the websites with more visitors and websites with good and high search engine ranking.
I'm surprised people are still discussing "Web 2.0", I haven't heard the term used in about 10 years! It never had any real meaning, when I first came across it people were using it to describe any site that used Ajax, then it got applied to everything. Is "Web 2.0" still a meaningful term?
Nah! Never was.
Web 2.0 Help you to make backlink to your website. And it will help you a little bit of Google Ranking. So Yes it helps.