Sql-server – Replication Configuration

You need to add a CNAME in your DNS at your primary SERVER putting the DR server's hostname. This way publisher.mainsite.mycompany.com can be resolved. Then use publisher as the hostname to use when connecting.

If you are using Transactional Replication then yes, this configuration is supported.

This is covered in Using Multiple Versions of SQL Server in a Replication Topology:

For all types of replication, the Distributor version must be no earlier than the Publisher version. (Frequently, the Distributor is the same instance as the Publisher.)

Since your Distributor version is a later version than your Publisher version, you are good here.

For transactional replication, a Subscriber to a transactional publication can be any version within two versions of the Publisher version. For example, a SQL Server 2000 Publisher can have SQL Server 2008 Subscribers, and a SQL Server 2008 Publisher can have SQL Server 2000 Subscribers.

Since your Subscriber is within two versions of your Publisher version, you are good here.

However, this configuration is not supported if you are using Merge Replication since your Subscriber will be a later version than the Publisher:

For merge replication, a Subscriber to a merge publication can be any version no later than the Publisher version.

If you have anymore questions, please let me know. I hope this helps.