The triggered ability counts all instants and sorceries that were cast before it resolves. If you cast instant spells in response to the ability, those spells will count.

The tokens copy exactly what is printed on the creature and nothing else (unless that creature is a token or is copying something else; see below). They don't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and/or Equipment attached to it, or any non-copy effects that changed its power, toughness, types, color, and so on.

If the copied creature is itself a token, the tokens created by Rionya copy the original characteristics of that token as stated by the effect that created it.

If the copied creature is copying something else, the tokens enter the battlefield as whatever that creature is copying.

If the copied creature has {X} in its mana cost, X is 0.

Any enters-the-battlefield abilities of the copied creature will trigger when the tokens enter the battlefield. Any "As [this creature] enters the battlefield" or "[This creature] enters the battlefield with" abilities of the copied creature will also work.