Add a domain that is the same of the FQDN server name

My server is called "cloud" and my domain is "mydom.tld"
Now I must create site and email for it, then I add a site "cloud.mydom.tld" and relative mail domain and some mailbox users.
I have found and resolve two problem:
1) SSL self signed and letsencrypt do not work. The home page and SSL certificate are those of the apache default and not those on /var/www/cloud.mydom.tld/{web,ssl}/*

Solution: modify the /etc/httpd/conf/httpd.conf and put the "IncludeOptional conf.d/*.conf" after (not before!) "Include /etc/httpd/conf/sites-enabled/". In this way, also letsencrypt work.​

2) Email send to @cloud.mydom.tld are routing to local user and not to ISPconfig user.

Solution: remove cloud.mydom.tld from mydestination at /etc/postfix/main.cf and restart postfix​

Now my question is:
These solutions are correct or there are other better solutions?
When I update ISPconfig, these changes are lost or not?
Many thanks for your reply.
Dario Lesca