Hello,

Global search doesn't work, for example: where {.name,.event_name} contains "error", though I send this fields from vector in json. Why?

You probably want display.name contains error. It is unlikely that .name and .event_name would contain error, but you can check with group by .name, .event_name what data you have there.

There is System combobox at overview screen, but I don't understand how send this field from vector.

This field is set automatically set based on the span/event/log attributes. See this for details.

Can I send metrics from vector?

Nope, Vector metrics are not supported at the moment. We might support them in future, but for now I would recommend using Otel Host Metrics. They are much better from what I can tell.