These and other answers can be found in the Newbie FAQ:
http://www.shrapnelgames.com/cgi-bin...;f=23;t=005518
Specifically:
5.9.7 To see a cloaked (level X) ship, you only need 1 kind of sensor (hyper optic, tachyon, gravitic, temporal, psychic) level X in the system. This sensor can be on any of your ships or sat’s, your ally’s ship’s or sat’s (even the ship/sat that is cloaked!!!). This does not take into account storm/nebula effects.
Slick.