Assigning IPs to resellers

[Atomic]

When creating cPanel reseller accounts:

 

Creating WHM reseller account creates account with "Allow reseller to use any available IP address.". We like to restrict IPs. How do most hosts achieve this? As it's setup so they can use any IPs how can the email template tell them what IPs to use for nameservers?

 

Also does not set main/shared IP to one of the reseller's IPs (as above). Will it also set up a resellers account so their shared IP is the server's main IP? No way to set on the second IP assigned to the reseller?