C: You can create a table in Dataverse and fill that table with data from an OData feed by using Power Query.
You can use the same techniques to integrate data from these online and on-premises sources, among others:
SQL Server
Salesforce
IBM DB2
Access
Excel
Web APIs
OData feeds
Text files
D: You can create a new Dataverse table that stores all the metadata from the dataflow run. For every refresh of a dataflow, a record is added to this table. You can also store metadata for multiple dataflow runs in the same table.
Reference:
https://docs.microsoft.com/en-us/power-query/dataflows/load-dataflow-metadata-into-dataverse-table
https://docs.microsoft.com/en-us/power-query/dataflows/add-data-power-query