Well, his build was originally premised on the idea of Rogue1/Sorcerer12 because he wanted the Rogue starting skills, and because he thought that a one level dip would put the Rogue class skills on his "In Class" list forever more.
He really wanted UMD, you see.
He may go Rogue2/Warlock 11, to gain the Evasion, but I showed him where, right in the book, it says the class skills are only in class when you're adding levels of that class.
So I'm not worried about his mighty 1D6 sneak attack.
I mentioned the Familiar issue and he says he plans to get the Pseudo-Dragon as a Cohort, rather than a Familiar.
My feeling about this player is that he is trying to build cool concepts, not necessarily effective ones. He really doesn't know the rules that well.
His cat-person, for example, supposedly had a base movement of 70. When I checked the Anthropomorphic Leopard build, it listed a base of 30, so I questioned him on it. He had used the Quick trait from Unearthed Arcana (not an approved book), and had a magic tattoo that gave Haste, always on.
I asked what book the Tattoo was from and he said Complete Arcane. The only mention of them in that book is to say that they're specific to Forgotten Realms, and that they work like potions. That is, it takes an hour to inscribe a magic tattoo, and then it can be invoked like drinking a potion. You use it, the effect lasts the same a s a potion of the same spell, and then the tattoo is gone.
He was surprised, since real world tattoos don't go away, ever.
The point is, he hadn't read the rules, did not even have the rule book it actually came from, but had heard someone mention it and thought he could just pay 750 (the price of a 3rd level potion) and be Hasted forever more.
So whatever he ends up with will have to go through a strict and severe review. Not becaues he's trying to break the rules, but because he's breaking them without realizing it.
I hate having to be the rules ogre in situations like this, but sometimes a rules ogre is what the game needs.