Right now there is no tool that is going to show you the DA authority over a period of time. However, you can look at the site's rankings over time if you were to use SEMRush.com. You can also download the site's backlinks, and using most link tools they'll show you the history of the links and when that site acquired a particular link.

You have a few options here. You could take a look at the popular bloggers in your industry and contact them directly. They already write content and are familiar with your industry, so they may be willing to work with your site directly to create content and manage it as a "ghost writer" or "ghost editor". You can usually end up having a good mutual long term relationship with someone specific that you may even to meet with in person every once in a while.

An alternative would be a company, but you may end up with writers and editors that are not located in your country or you might have to deal with a higher turnover rate with employees.

There are firms such as our firm that manage content and have an internal staff that can handle your needs; it's important to make sure that the writers are familiar with SEO best practices and can also help promote your content properly, as well.

Generally speaking, if that's the only H1 tag that is going to be on the page, then it should be just fine. I would style the text so that it looks appropriate for the page and looks like the rest of the breadcrumb text on the page. An alternative would be to select another location, such as the sidebar somewhere towards the top of the page, and include a heading as an H1.

I don't understand why you believe you need to add a refresh on the page. Even though you are posting new content on the page, there is no need to refresh the page. Users will refresh the page themselves, or they will just come to the page and see the updated content. The search engines will naturally know that the site contains new content: they will see that you have added fresh content on the site (new news items) and will come back.

I would not include any sort of refresh on the page. You might include a message on the page to tell users to refresh the page for the latest content, but that's all I would do. I do not recommend any auto-refresh.