...Ahmand is "MIA" during this part of the mission
Armand is in the very last warehouse (near the Bloated Float), in the basement. You should be able to break in and find him. He's just sitting there in a chair, hanging out.
S'Krivva should be in or around her house regardless of Armand telling you about her. She is out and about a lot.
S'Krivva is usually at home reading or eating in a chair in the southwest corner of her house, but she also eats lunch at Silverhome on the Water at noon (12.00 PM). You can find her at the Lonely Suitor Lodge in the evening around dinner time, as well as all day Tirdas and Turdas.
I think I read somewhere that she goes to the Skooma Den occassionally, but I can't remember right off.