How can I make Visual Studio wrap lines at 80 characters?

Tools >> Options >> Text Editor >> All Languages >> General >> Select Word Wrap.

I dont know if you can select a specific number of columns?

Unless someone can recommend a free tool to do this, you can achieve this with ReSharper:

ReSharper >> Options... >> Languages/C# >> Line Breaks and Wrapping

• Check "Wrap long lines"
• Set "Right Margin (columns)" to the required value (default is 120)

Hope that helps.