Multiple HTTPS sites with multiple Certificates under the same Virtual Server

For this case,

1. Separate new pool for the new server.
2. Yes you can use LTM policy or iRULE to send traffic to the desired pool based on the URL host; uri etc.

NOTE- Adding a new pool member in existing pool will create problem. As for any host request, the request will be forwarded to all the active pool members in the pool. So with this, client will get unexpected response pages.

Hope it helps!