For your first question, yes you can filter your based on date or any specific value. If you go to link below, you will find “Query submitted data” section which will give you the idea of how to query your data though any value you want. You can find more details on conditions in the mandodb’s link. If you have more questions let me know.
https://eu.kobotoolbox.org/api/v2/assets/{your forms uuid}/data/
https://www.mongodb.com/docs/manual/reference/operator/query/
You also can check this previous discussion API v2 querying by _submission_date
