How does Totem Armor work?

Totem armor doesn't destroy the Aura; rather, it changes the effects of the spell or ability. On the other hand, if a spell or ability deals lethal damage to a creature enchanted with an Aura that has totem armor, the game rules regarding lethal damage cause the Aura to be destroyed, not that spell or ability.

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Keeping this in consideration, can mirage mirror copy aura?

Mirage Mirror will wind up as a copy of the permanent targeted by the last ability to resolve. If Mirage Mirror becomes a copy of an Aura, it's put into its owner's graveyard unless it's somehow attached to an appropriate object or player already. Do clones copy counters? It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its power, toughness, types, color, or so on.

Can clever impersonator copy a Planeswalker?

If Clever Impersonator enters the battlefield as a copy of a planeswalker, it will enter the battlefield with a number of loyalty counters on it equal to the loyalty printed in the lower right corner of the planeswalker card. It won't copy the number of loyalty counters on the original planeswalker. Does exile remove auras? Unless the card/ability specifically says that it effects anything attached to the creature, like the rules for phasing, it ignores them. In this case it means that any auras that were attached to the creature exiled by the banisher priest remain on the battlefield not attached to anything.

One may also ask what happens to equipment when creature dies?

Nothing. It stays on the battlefield, not equipped to anything.