Hi Andre
1. In both Windows MSCS cluster nodes SAP instance kept on. when the system performing failover to node 2 it will start automatically.(it mean that any failure in the node 1 and during this process both nodes SAP instance should be on)
2. How you are making the node 2 goes offline? by manually or automatic?
3. Kindly refer the Windows MSCS FAQ link which will address all your query
High Availability - Frequently Asked Questions
Regards
Sriram