How many publications to list as "selected"? I'm applying for CS tenure track positions this year, and was advised to add a "Selected Publications" part to my CV (out of 20+ conference and journal papers). How long should this section be? Can I pick all my top-tier publications (seven) or do I need to select among them?
I would certainly include them all (the seven). Even more than the seven top tier ones. If you were an old hand in academia with hundreds, then you select. A young starter-upper should include a much larger fraction of the published work. 

Don't neglect that in CS, conferences are usually primary. 

But seven seems too few if you have more than 20.