Central Instance failover on NW70 WIN2008 Cluster

Hello Experts,

after reading a lot of forum threads about Netweaver 7.0 Central Instances in cluster, it's not yet clear for me how it works.

If there is only one CI in the system installed on a "local disk" of the cluster, how is it protected from failure? In 4.70 I had the CI on a shared disk with a virtual name. I could failover it from node to node with no problem. How does it works in NW70?

The Dialog Instance installed in the other cluster node can work as a CI if I shutdown the real CI on the first node?

If this is true, I need to change the profile of the dialog instances to have all the required processes needed by the system

to work properly (UPD, SPO...)

Let's have an example:

I finished to install my WIN2008 2 nodes cluster with SQL2008 DB instance and also installed the Central Services (ASCS) instance on a shared disk. And now? If I understood I should:

1) install the CI in one node of the cluster and a Dialog Instance on the other node.

2) change the DI profile to have the some number and type of precesses running on the Dialog and on the CI.

3) create a logon group with both the CI and the DI and any aditional Instance running on external servers.

4) configure the SAPLOGON to use the logon groups specified on SMLG, using as "Message Server" my ASCS virtual name.

Is this ok? This means that I will no more have a virtual server name available to my Sap server. Is this right?

Thank you