If a domain has a high DA (Domain Authority), does that mean my blog will have the same DA?
No, not necessarily. Some platforms, like WordPress and Blogspot, don’t always pass their DA to subdomains. However, with Livedoor, I managed to get a DA of 55 for my subdomain, which isn't bad at all. You can verify this using your preferred tools.
So, how will the new blog help if the answer is no?
This is a Web 2.0 site, which can help you create do-follow backlinks for your main site. These platforms typically have a good indexing rate.
Does the article need to be original, or can it be copied?
Never submit copied content. The article must be original, though you can use spun content. However, the quality of the article will influence the results. For example, the article I submitted on Livedoor got a few impressions and clicks, which I can track in the webmaster tools. Treating it as a main blog will yield better results.
If this helps, would creating a few blogs on Blogspot with links to my main blog improve its ranking?
Instead of creating multiple blogs on Blogspot, aim to get backlinks from different domains. Ranking depends on more than just backlinks; other factors are crucial too. You can find comprehensive information about on-page and off-page SEO on forums like BHW.
But doesn't Google disregard backlinks created by the owner?
I'm not sure why you think Google doesn’t count owner-created backlinks. If you're using the same IP, email, and webmaster tools, Google will know you're the same owner creating backlinks. To avoid this, use different IPs, emails, and webmaster tools. Every site owner creates backlinks, but it's essential to do it correctly.
Should I create new blogs with different emails?
Yes. Use just one blog linked to your webmaster email. For backlink submissions, create new email IDs and change them often to avoid being flagged as spam.
I've tried to provide the best answers based on my knowledge. Conduct your research, read forums like BHW, and experiment to see what works for you. Remember, SEO is more about how you do things rather than just what you do.