The textures for the Asari are mainly in the BIOG_ASA folders. The heads in BIOG_ASA_HED, and the clothes/armour in the BIOG_ASA_ARM. Aria's face is coloured and managed by the game, so her texture would be shared by the base, ASA_HED_PROBase_Diff, located in ProBase inside BIOG_ASA_HED_PROMorph_R.
Aria's outfits are located in biog_asa_arm_ari_r\ARIa\textures, and her Omega DLC outfit it located in BIOG_ASA_ARM_ARA_R (If you just click the folder itself you get the facial marking texture for the DLC) and inside textures.
Liara's Romance Body is located in BIOG_ASA_ARM_LIA_R\LIAd.
Samara's body is located in BIOG_ASA_ARM_SAM_R\SAMa\Textures.
If there's anything else, please don't be afraid to ask~