bonus objective on Doomday delivery(Last mission)

[Bostonasian]

I know one is to blow up the helicopter, what is the other one?
I see there are 2 bonus objective.

[breath of life]

It is to listen into Mallard (the guy from the first level) and some other russian talking about how they set you up.

They are right below that chick that doesnt feel pain, just shoot her in the head, and they wont know you are coming.

[crackhead skny]

if you capture valeska, u get a bonus.

[The mOBSCENE]

in the engine room if you put a C4 brick on that and blow it up, its another bonus.

[RadioactiveMan]

Another way to hear the guys talking is to sneak to the other end of the boat. Move stealthily down the path where you start. When you reach the part where the wall to your right disappears, the guys that you have to listen to are right around the corner.