?que pasa? (very informal)

?que tal? (saying hello)

• Bien (good) ?y.tu?

• Muy bien (very good)

‘Por’ vs ‘Para

• ‘Por’ connects actions, situations or ideas taking place over the same period of time

• ‘Para’ connects actions that take place separately, in chronological order first

A: Estudio espanol por mi trabajo
B: Estudio espanol para trabajar en Espana
Person A needs Spanish for their current job. Person B needs it for a future job

You can not use por or para before a infinitive. Instead use porque before the infinitive