How to get Instant Overview

Often, Excel is used to evaluate given data. Which values are critical? Can I see at a glance what the development was like? Can I highlight a whole row if one column has important content? Or ask for the content of two cells, simultaneously? How do I get overview in a thick workbook? How do I get a clear and telling chart? Is there anything as clear, but not as large as a diagram? Can I ask Excel in natural language without any formula?
All these questions are answered here.