Translation of "Preconceptions" in Spanish

Of many ideas and preconceptions I had before.

de muchas ideas y preconceptos que yo traía de antes.

Let's forget about preconceptions, enjoy learning although it is tiresome.

Sacudámonos los prejuicios, disfrutemos de aprender aunque dé fiaca.

He had to have no preconceptions, he didn't know the error rates,

Él no tenía ideas preconcebidas, ni sabía de las tasas de error,