New domain-issues and search plugin

Hello WordPress

I had a quick look at https://www.ads-software.com/support, but I can’t see where I can find answer for these questions in the forums, so I give it a try in a new post …

The content of the website I admin was recently copied to a new .org domain, and the old .com site was removed and the domain changed to a pointer. Note; it’s not a migration, but an exact copy.

I discovered several things though regarding photos and links:
1) The photos in already sent newsletter can’t be seen since the photos (seemingly taken directly from database?) link to old website urls, and the pointer only link to the frontpage of the new.
Question: For people to be able to see old newsletter with photos; would a solution be to make a code/command in the htaccess-file (at the web host admin) to include the rest of the picture url, like a redirect code?

2) I had to manually change some .com- links to .org-links in the content on the website, but I think there are more old links. All the photos and pages obviously have the right address since it is a new website created from the new domain (as I meaning, not migrated).
Questions: I haven’t had the need for it before now, but it doesn’t seem that there is a built in search function in WP back end, or is it?
I found though there is a plugin that can crawl the site, “Search & Filter”, but when I search for the plugin, it doesn’t show. Something to be downloaded … how does that work in the back end?

Thank you for your time!
Kindly regards
Ingunn Borren

The page I need help with: [log in to see the link]