Can I look at an arbitrary date range?

Yes. The range picker takes presets for the usual windows and a two-month calendar for anything else, so a campaign week or a single Black Friday weekend is as readable as a month.

The range lives in the URL, which means a particular view can be bookmarked or sent to somebody else and will open exactly as you left it. Insights uses the same picker, so the two pages can be pointed at the same window.