Alandra, Sognatrice del Cielo

The first triggered ability can trigger only once each turn. It doesn't matter whether Alandra, Sky Dreamer was on the battlefield when the first card was drawn. If it's not on the battlefield when the second card is drawn, the ability can't trigger at all that turn. It won't trigger when the third or fourth card is drawn.

The same is true for the last ability and the fifth card drawn.

The value of X is locked in as the last ability resolves. The bonus it grants won't change after that point, even if the number of cards in your hand does.