1. It depends on the URLs it will serve. If they're the same, then you can simply export the certificate from the existing server and import it into the new one as long as the private key is exportable.
2. The two servers should find out about each other and route mail with no additional configuration as long as you haven't made any configuration changes to the Default receive connector that would break it.
3. You can't configure IIS so that will happen. You will need, NLB, a load balancer or the like.
Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."