some ragdolls qeustions (and A mini texture thing)

Well I downloaded the star wars packs, (mainly the mega star wars, stormtroopers and clones pack) and installed them…they work so far but one thing i didn’t get how come some npc models (for example the dc vs mc joker npc model) don’t show up as npc’s but only as ragdolls, I heard of npc that are to old will not work. but is there a way to fix it? I know some ragdolls tricks like how to make one run but when you need them to walk it is hard without npc parts. so is there an easy way to make the ragdolls npc again? or is there a god way to make ragdolls walk?
PS is there a program or a way to find missing textures from maps. (I know some maps require extra textures from other source games but I never know what source game.) If I can find the name for the missing texture I might find the game it needs (Some map up-loaders forget to add what other game it requires.)
I don’t know if this is the right place or if others asked this stuff already but I found nothing in the search option.
and I also wanna know how to make secondary skins, like the hl2 train boxcar.
PS excuse bad grammar I am not originally an english speaker.