Question on Cloaking and Sensors

[Enigma]

Do planets automatically detect cloaked ships at the highest your highest tech level or do you need to have sensors on ships or satellites?

Is there a range factor? Or does it just have to be in the same system?

To attack the cloaked vessel does the ship have to be in the same hex with the cloaked ships and your other ships?

Can all ships in a fleet attack a cloaked vessel even if only one ship has the appropriate sensor?

Thanks