The hostages you need are as follows
Pizepi Jorgen: To save Pizepi, you need to reason with "The Gift" for her safe release. Use kiss ass 8 to get her out safely.
La Loca: You need to kill the breathers in the kitchen and grab the key from their bodies. After that, open the freezer and talk to her.
Rook: You need to kill some breathers in a suite to get to him. After getting to him, you need to unlock his cell (Lockpicking 1) and treat his wounds (First aid 1)
Reed Twins: In the same connecting room as Rook are the Reed twins. To save them, you need to interact with the electric box and disconnect it (Mechanics 8)
Estin Ward: You need to kill all the breathers in the pool first, then interact with computer and open the sauna door (Nerd stuff 8)
The other 2 hostages aren't needed (Llewelyn and Gwendoyln Reed)