rDNS/PTR - ask your host provider or ISP, Ditigal Ocean and Vulture have options for this so you won't bother them.. be warned that this 2 provider are unmanaged,you fix your server on your own.
DKIM - you can use opendkim
yum install opendkim
cant' remember is WCP have this on default, been long since I last use WCP, I moved to another control panel since I need CentOS 7 and WCP only support 6.
SPF - You need to set this up in your domain name with the mail pointer..
coderinthebox.com. IN TXT "v=spf1 a mx a:coderinthebox.com ip4:45.63.122.247 ip6:2001:19f0:7000:9e47:5400:00ff:fe0d:279c ?all"
MX you should have a default and working MX record with WCP. Sometimes, you need to edit it.