Regarding the controversy about what to include in an estimation of a person's vocabulary: estimates of the size of Shakespeare's vocabulary range from 15,000 to 30,000 words, depending on what you decide to count. Here the question of counting method is crucial, since the scholars working in this area base their estimates on the same body of texts. The one who arrived at the highest word count regards the different forms of a word (such as cry, cries, cried, criedst) as separate words. He also includes proper names in his estimate. This does not address your question directly, I know, but indicates another kind of problem encountered when estimating vocabulary: what is a word? Regarding the question whether passive vocabulary should be included in such a count, I would say yes, since most of us use only a small part of our vocabulary actively and otherwise the numbers we would be looking at as estimates would hardly serve to satisfy our vanity. Isn't that what this question is all about, anyway?
