Yes for the time being, the platform is free to use. It will be most likely stays free for all base features. Some features might require more hardware and development could be introduced later on.
No, you don't need to sign in to use the platform but you'll miss out on handy features. If the feature is free and it doesn't login, you won't need to login.
Yes, the website is secured with SSL on an up to date dedicated server and the data is stored in an isolated SQL database. The credentials are not used for anything than what you're browsing. No data is not shared with any third party.
No, all your data is retrieved on demand from GCP and it's not stored nor logged.
The company I currently work for, Teads, uses BigQuery as a data warehouse. And though I feel like BigQuery and GCP are already providing a great service, I believe it could go further on some aspects and that's what this platform tries to bring.
Maybe if there's a demand for it. Feel free to contact us.
Answers for general questions about query analyzer tool
There are 2 ways to go:
If you have access to BQ CLI, you can use following command to output the JSON Job into a file: bq --project_id=[projectId] show -j --format=json [jobId] > myJsonJob.json