it will be always open.
 because the market is on. absolutely yes
if there is no dump and pump it meas no transaction in the market.
it usually happen not only in bitcoin but also in all business in this world.
yes many people said that pump and dump is one of the strategy for someone who has a lot of coin.
they play market and try to make the price.
but increasing or decreasing peice also depends on the news about the event token.