Yes, the real price is adjusted and then other buy and sell orders take over from there. Let say CPV was $21, the open would be consider $20.60 if it was ex-date for $.40. If CPV closed at $21 that day that would be considered up $.40 on the day.
Yahoo and their historical quotes adjusted for past dividends. I generally find that confusing because you're looking at prices that never really traded at in somecases. WWW.bigcharts.com I don't think adjusts for dividends.
EX = "WITHOUT". Therefore, anybody who buys the stock "ex-dividend" tomorrow does not get the divvie. This assumes Yahoo's ex-dividend date is correct, which it should be, because you take the record date (Nov 15) and subtract two days. Why it fell today I don't know. It has been selling off a bit last 5 days. http://finance.yahoo.com/q?s=CPV&d=c&t=5d&l=on&z=b&q=l I guess the late sell off today was some folks who don't want divvie income.