FT: sensors

Are Active sensors 360 degrees?

Can fighters make any sort of identification before making an attack?
(I recently was in a battle when the enemy's 24 torpedo fighters
attacked 
my smallest ship not knowing anything about my fleet composition)

Can a capital ship, which gets 3 sensor rolls, target an object for 2 or
3 rolls in the same turn?  Or must it choose a different target for each
roll?

Glen