Some abilities trigger "whenever you sacrifice a Clue". Those abilities trigger whenever you sacrifice a Clue for any reason, not just to activate a Clue's activated ability.

Any choices made when the spell resolves won't have been made yet when it's copied. Any such choices will be made separately when the copy resolves.

Some spells and abilities that investigate may require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won't resolve. You won't create any Clue tokens.

You can't sacrifice a Clue to pay multiple costs. For example, you can't sacrifice a Clue token to activate its own ability and also to activate Alquist Proft, Master Sleuth's ability.

You can't choose to pay any additional costs for a copied spell. However, effects based on any additional costs that were paid for the original spell are copied as though those same costs were paid for the copy too.

Clue is an artifact type. Even though it appears on some cards with other permanent types, it's never a creature type, a land type, or anything but an artifact type.

If a spell or ability has damage divided, the division can't be changed, although the targets receiving that damage still can. The same is true of spells and abilities that distribute counters.

If the spell that's copied has an X whose value was determined as it was cast, the copy has the same value of X.

The copy will have the same targets as the spell it's copying unless you choose new ones. You may change any number of the targets, including all of them or none of them. If, for one of the targets, you can't choose a new legal target, then it remains unchanged (even if the current target is illegal).

If an effect refers to a Clue, it means any Clue artifact, not just a Clue artifact token. For example, you can sacrifice Wrench to pay for Alquist Proft, Master Sleuth's activated ability.

The copy is created on the stack, so it's not "cast." Creating the copy won't cause abilities that trigger when a player casts a spell to trigger.

If the spell that's copied is modal (that is, it says "Choose one —" or the like), the copy will have the same mode. A different mode can't be chosen.