When applied to a dataset, this role provides the ability to read the dataset's metadata and list tables in the dataset. When applied to a project, this role also provides the ability to run jobs, including queries, within the project. A member with this role can enumerate their own jobs, cancel their own jobs, and enumerate datasets within a project. Additionally, allows the creation of new datasets within the project; the creator is granted the BigQuery Data Owner role (roles/bigquery.dataOwner) on these new datasets.
https://cloud.google.com/bigquery/docs/access-control

Nearline, Coldline, and Archive offer ultra low-cost, highly-durable, highly available archival storage. For data accessed less than once a year, Archive is a cost-effective storage option for long-term preservation of data.
Coldline is also ideal for cold storage-data your business expects to touch less than once a quarter. For warmer storage, choose Nearline: data you expect to access less than once a month, but possibly multiple times throughout the year. All storage classes are available across all GCP regions and provide unparalleled sub-second access speeds with a consistent API.

as the instances (normal or preemptible) would be terminated and relaunched if the health check fails either due to application not configured properly or the instances firewall do not allow health check to happen.
GCP provides health check systems that connect to virtual machine (VM) instances on a configurable, periodic basis. Each connection attempt is called a probe. GCP records the success or failure of each probe.
Health checks and load balancers work together. Based on a configurable number of sequential successful or failed probes, GCP computes an overall health state for each VM in the load balancer. VMs that respond successfully for the configured number of times are considered healthy. VMs that fail to respond successfully for a separate number of times are unhealthy.
GCP uses the overall health state of each VM to determine its eligibility for receiving new requests. In addition to being able to configure probe frequency and health state thresholds, you can configure the criteria that define a successful probe.