The first error indicates that one input failed to start on one of your hosts. So that’s not altogether bad news. Question is: which input is it? I can’t tell from the numbers shown. Could it be that this particular input is told to run on a port <1024? Because that won’t work without extra trickery.
The other two messages indicate that Graylog is not able to push messages into ElasticSearch. Either ElasticSearch is refusing to accept your input, or Graylog cannot find ES. Since you are using the vendor-provided OVA, the latter is unlikely. Unless you went into the configuration and manually made changes.
When you go to System > Overview, what does the ElasticSearch status bar say? It -should- report that the Elastic status is “green”.
Unfortunately, the fact that earlier Graylog could not show you any indices suggests again that Graylog simply cannot talk to ElasticSearch. Either because ES is down, ES is broken, or because you manually made changes to the config file for Graylog.