Too long titles are not recommended. The optimal length is around 50-60 characters: https://moz.com/learn/seo/title-tag

It's OK to update the title and metas over time. That's one of the common steps to improve SEO.

Disavowing the spammy domains is not supposed to reduce the spam score because Moz has no visibility of the GSC disavow list. If you disavow a spammy domain you can reduce its negative impact from the Google perspective, but your own spam score will remain unchanged.

First of all, Google doesn't use Moz spam score: https://support.google.com/webmasters/thread/2440327?hl=en

So, if your Moz spam score is high because of "spammy" backlinks it doesn't mean that Google considers your site as spammy. You can check the spam score for every linking domain in the Link Explorer. If there are too "spammy" domains take the necessary actions (disavow them in GSC as the last resort).

Apparently Google doesn't care: https://support.google.com/webmasters/thread/21223241?hl=en

From the webmaster point of view it seems like more work to configure each individual property and review every report separately.

There are high DA domains like google.com. So, there is nothing wrong with having backlinks from .com domains. It's always recommended to check the authority and spam score for every linking domain regardless of the domain extension. The point is that ".com" is not necessarily lower quality than ".co.uk".

This is a common question in this forum.

Maybe you got some new backlinks with low DA or maybe you've lost some high DA backlinks. You can start looking into your linking profile in the Moz Pro report. More info in this old thread: https://moz.com/community/q/why-my-domain-authority-da-is-decreased-from-21-to-19

The redirects are intended to keep link juice when migrating to a new domain. Actually they just help the existing users find the new domain. If there are redirects to your domain from unrelated websites the Google bot should be smart enough to ignore them. That's why it's better to have backlinks from unrelated sources than redirects.

Most youtubers don't mind their videos being shared. The more they are shared the more views and likes they will get. Just make sure to credit the author.

I'm not sure I understood the question. Are you using the term bookmark referring to this part of the URL: "#auto" ? This is appended to the URL to make it refer to a specific point in the page or a page fragment. It's not the same as a bookmark.

When migrating the site you can add the same IDs in the new pages to preserve the fragments. Otherwise the URL will open the whole page by default (if the ID was not found).

You need to check the HTML code of the link. If it doesn't explicitly say nofollow in the rel tag then it is a dofollow link.

For example, this a nofollow link:

<a <strong="">rel="nofollow" href="https://www.mywebsite.com">Visit my website!</a>

If we remove the nofollow property the link becomes dofollow:

Visit my website!

If the PA and DA are low the page can still appear in the first position if it contains a very specific and informative answer to the user query. So, if you are promoting a very specific topic you can just improve the content quality of your pages to appear near the top. However, if your topics / keywords are too generic you really need to improve your authority.

In the long run it's always good to increase your DA/PA. Blogs and media sites are eager to link to high authority contents, which can increase your credibility even more.