Yes, the sensors all work. They even coordinate with the sensors in a ship whose cockpit is occupied by a friendly.
But bio-sensors and multi-sensors have one significant difference: bio-sensors will not sense unfriendly ships, nor will they sense droids. Multi-sensors sense everything in range.
I have a question on a similar tack:
I notice when my ship sensors say 15 to a target, when I step onto the surface, the range then is 17. When the surface range says 15, the ship's range says 11.
To quote the sketch from SNL, "What's up with that?" Can they be synchronized so that they say the same thing?
Note this mostly happens along diagonals. When using straight up-down, left-right rangefinding, I see less of this.
I can't check right now, but I do believe you automatically share senors with droids whether you have a sensor pack equipped or not.
I do know for a fact however that as long as you have a sensor pack equipped you automatically share sensors with any droids you own, or that someone who is on your iff as a friendly owns.