Install Nginx First Install - Xenforo running - but got some questions

Please fill in any relevant information that applies to you:

• CentOS Version: i.e. CentOS 6 32bit or 64bit / CentOS 7 64bit ?
• Centmin Mod Version Installed: 123.09beta01
• Nginx Version Installed: 1.19.1
• PHP Version Installed: 7.3.x
  
• MariaDB MySQL Version Installed: 10.2.xx
• When was last time updated Centmin Mod code base ? :
  
• Persistent Config: Do you have any persistent config file options set in /etc/centminmod/custom_config.inc ? You can check via this command:
  
  Code (Text):

  NGINX_SSLCACHE_ALLOWOVERRIDE='y'
  SET_DEFAULT_MYSQLCHARSET='utf8mb4'
  ZSTD_LOGROTATE_NGINX='y'
  ZSTD_LOGROTATE_PHPFPM='y'
  PHP_PGO='y'
  PHP_LZFOUR='y'
  PHP_LZF='y'
  PHP_ZSTD='y'
  DUALCERTS='y'
  LETSENCRYPT_DETECT='y'
  ###############################################################
  # Cloudflare DNS API for DNS Mode
  # https://github.com/Neilpang/acme.sh/tree/master/dnsapi
  # login to your Cloudflare account to get your API Key in
  # My Settings section of your account
  # to ensure these settings persist DO NOT change them in this
  # script but set these variables in persistent config file at
  # /etc/centminmod/acmetoool-config.ini
  # set to CF_DNSAPI='y' and fill in CF_KEY and CF_EMAIL settings
  CF_DNSAPI='y'
  CF_KEY=''
  CF_EMAIL=''
  ###############################################################
  AUDITD_ENABLE='y'
  

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So. First of all thanks for the stack. I was long time affraid off it, cause there are so many informations, but so far it is working good. My problem was that i cant do http01 challenge cause the dns is not pointing on my ip.
So first off all:
Is it possible to disable the main host? Im afraid about leaking my ip through the hostname.

Second: Caching for Xenforo: I got still a small forum but it is growing. 120-150 Member. Should i stay for Redis or Memcached ?

Last one: Firewall: Im only using the 443/80 Port for Web at outgoing service. And i need to only allow to access my Reverse proxys provider ip (ip, proxy ip).
SSH i would open for my static IP. I dont understand CSF so far..

Thanks for Help and Regards!