Learn Russian: Ничто меня не удивляет, даже это событие. - Nothing surprises me, not even this event.

Russian requires a double negative. When you use a negative pronoun like ничто (nothing), you must also put не before the verb. In English, two negatives cancel out, but in Russian, they work together to make the sentence negative.

Why use Ничто here instead of the much more common word ничего?

Ничто is in the Nominative case, meaning it is the subject of the sentence (the "Nothing" is doing the surprising). Ничего is the Genitive or Accusative form, which you use when "nothing" is the object receiving an action.

Why is меня placed before не удивляет? Could I say Ничто не удивляет меня?

You can absolutely say Ничто не удивляет меня, as Russian word order is flexible. However, placing the object pronoun (меня) before the verb is a very common and natural habit in Russian.

If this sentence were in the past tense, what gender would the verb take to match Ничто?

The pronoun ничто (just like что) is grammatically neuter. So, in the past tense, the verb would take the neuter ending -о: Ничто меня не удивляло (Nothing surprised me).