This may be multiple separate issues, however, I think its sensible to start with the initial rebalance failure, and investigate from there. Please feel free to separate the issues if required.
A user on the forums has a two node cluster which has failed the initial rebalance due to the indexing service, they're now unable to interact with the cluster in a useful/expected manner. The issue is manifesting with the following symptoms:
1) Loading a sample bucket has failed (due to a timeout waiting for the bucket to report as healthy)
2) The user is unable to insert documents into the created bucket
3) ns_server appears to be timing out when communicating with the indexing service
4) Successive rebalances are now failing
5) Indexing appears to be failing to communicate with the projector
From the logs we see a few interesting things worth noting: