The reason that Czerka is enslaving wookies is because the neighbooring system to Kashyyyk the Tanshions( the aligator guy's people from Empire strikes back)
want the wookies enslaved because the wookies and aligator people are enemies.
The tuskin raders are animals they kill all ravege all and destroy all. they fear technology and fearing technology only gets you killed in the long run.
The Selkath are fish and fish dont like humans because humans like fish sticks!
the selkath are like the Protoss only... the Protoss would waste the selkath!!!
THe selkath are neutral and only want to sell their kolto to everyone.