"[Of the words in a dictionary] ... most people know half the words - about 50,000 - easily. A reasonably educated person about 75,000 and a really cool, smart person well, maybe all of them but that is rather unusual.
"An ordinary person, one who has not been to university say, would know about 35,000 quite easily."
That came from this article.
However, we don't use the same number of words that we actually know. Then there is the fact that lots of people have a great vocabulary but can't actually spell very well. So the number of words we know doesn't equate to the number of words we can spell.
2. When you say "proper names" are you including everything: people's first names, the names of famous landmark buildings, countries, brands, company names etc etc?