In my point of view, Alexa rank calculates on the basis of Alexa toolbar installed and visited to the website. So i don't think it relates to the google serp rank. better focus on seo tactics implementation.
Create high quality content, share on PR sites, Implement SEO tactics, get quality backlinks from relevant industries, make your presence on social media channels etc are the SEO techniques in 2017.
Domain Authority (DA) is a score board developed by Moz that helps to know how well a website will rank on (SERP). We calculate Domain Authority by considering many metrics — linking root domains, number of total links, MozRank, etc.
Title tag describes what is the webpage about.. It tells the users what does the page contains, so it useful for user to know about the page and its one of the ranking factor of search engine.