To see exactly who viewed a dashboard and when, your best bet is the History Explore (Admin > System Activity > History).
While Looker does have a "Content Usage" explore, the "History" explore is much better for granular, event-level data. Here is what you'll want to pull:
To find when: Use the History > Created Date (or Created Time) dimension.
To find who: Bring in the User > Name dimension.
To identify the dashboard: Use Dashboard > Title and Dashboard > ID.
Pro-Tip: Filter History > Source to Dashboard to exclude automated scheduled deliveries, API calls, or Explore queries. This ensures you are only looking at actual human views.
Yes. In the History Explore, Looker automatically joins the Dashboard metadata to the Folder metadata.
Simply add a filter using the Folder > Name or Folder > ID dimension.
(Note: In some older Looker backend tables or documentation, folders are occasionally referred to as "Spaces", but in the frontend Explore UI, it will clearly be labeled as "Folder").