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.

Briarbridge Patrol's second ability looks at the entire turn, even if Briarbridge Patrol wasn't on the battlefield for some of the turn. It will see Clues sacrificed for any reason, not just Clues sacrificed to their own ability.

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 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.

Briarbridge Patrol's first ability will only trigger once per combat damage step, regardless of how many creatures it deals damage to.