Nice bookmark for the heads:
Next to those names you have the dark side transition variations, it's similar for the portraits. For example PFHA01.tpc/tga is the neutral/light side version, then there's PFHA01D1 for half way towards dark, and PFHA01D2 for max dark (I don't think it's actually 50% and 100% dark, but something like that).
The appearance.2da info here helps for the other things:
There you can find that for example column modela points to the underwear model, texa to the accompanying texture.
Now on to the actual filenames, for example the first player entry in appearance.2da "P_FEM_A_SML_01" has PFBAMA in the texa column. Those letters come from
Player
Female
Body
A (the underwear column)
M is a bit of a leftover from K1, which has different underwear for different classes (S, M, L)
A for Asian/Hispanic (btw B = "Black" & C = "Caucasian")
Finally there is a number, a texture variation number that's in the item file (.uti). For underwear it's just 1 (always 2 digits so 01). Final filename: pfbama01.tpc/tga (case insensitive). For other outfits there are different texture variations.
Advanced:
To find which texture an item uses you first again use "Detailed info of 2da files" to look up the column.
For example the n columns are for the Jedi Knight/Master model. In column texn you find PFBN (Sticking with the P_FEM_A_SML_01 row, although the skin colour is not relevant here, there's no A for Asian).
Now you need to find the texture variation number for a certain item (robe). You need to find the item template file (.uti). You can look it up at GameBanshee.
Random example: Dark Jedi Knight Robe
-> Template: a_robe_14
Now you open that item template (Kotor II -> BIFs -> templates.bif -> Blueprint, Item -> a_robe_14.uti), you find that the texture variation is 4 (-> 04). Final filename: PFBN04.tpc/tga.
I hope this is a good intro, good luck!
Feel free to ask more questions here or on the Discord.