HA failing to configure at 97% is often related to DNS resolution issues. Please double check whether this is ok and resolve any issues (see http://kb.vmware.com/kb/1003735)
Disconnecting and reconnecting a host from a vCenter Server environment - even with powered on VMs - isn't usually a problem, unless you use advance features like vDS or run workloads which require the host being managed by vCenter Server. Anyway, since you have Enterprise licenses, you should be able to vMotion the VMs to other hosts if required.
André