Q1. I’m inclined to not trust this message on this site and think it’s nothing to worry about. It states clearly below that the certificate covers mail.yoursite, www.yoursite and yoursite. I couldn’t reproduce this error trying a couple of other ssl checker services such as https://www.sslshopper.com/. It’s also notable that in the little mouseover ? help icon, they have the ‘Lorem ipsum’ text which greatly decreses my trust in the output of this service
Q2. Your rewrite rules have these lines:
RewriteCond %{HTTP_HOST} ^mdavis.photos [NC].
RewriteRule ^(.)$ https://www.mdavis.photos/$1 [L,R=301]
Which mean ‘when the host starts with mdavis.photos exactly, then do a 301 redirect to the same page on www.mdavis.photos.
If you want the opposite, you’d need to change this to something like this:
RewriteCond %{HTTP_HOST} ^www\.
RewriteRule ^(.*)$ https://mdavis.photos/$1 [R=301,L]
Which says ‘if the host starts with exactly www., then redirect to the same page on mdavis.photos
You would need to double check that your WordPress settings aligned with this (i.e. did or did not have www. subdomain) as maybe WordPress will do some fun stuff with also trying to add/remove the www.
HTH, please post response if you have more questions