Manual sql failover machine with replication
Yes, if you are using Peer2Peer replication between the primary and secondary servers which is an enterprise only feature
I would personally use Mirroring/AlwaysOn for redundancy between primary and secondary sites as this includes ways to failover without changing the DNS records. Either by adding ';Failover Partner=PartnerServerName;' to the connection string or by using Availability groups with multisite failover 
Mirroring or AlwaysOn, depending on your SQL Server version - or Peer2Peer replication.
Using Mirroring or Availability groups this will in most cases simply by achieved by bringing the server online and the service will automatically send all the changes over and then you can manually failover.