Yes, the first vmnic is used unless it fails, in which case the next one takes over. Keep in mind that this will effectively make vmnic4 a standby vmnic in this case.
No actual load balancing is available with this policy. The virtual switch always uses the uplink that stands first in the list of Active adapters from the failover order and that passes failover detection criteria. If no uplinks in the Active list are available, the virtual switch uses the uplinks from the Standby list.
