In case this is useful for anyone else, I've found some information that answers my questions:
1) Section 26.2 of the Qlikview Server Reference Manual has instructions for how to cluster the DSC service, which should make this service resilient.
2) Section 26.1 deals with how to cluster the QDS (i.e. ReloadEngine), so I won't need a 3rd party clustering mechanism for this. However ,it looks like I will something like Microsoft Cluster Server to provide resilience for the QMS.