Hey, nite!
About Obfuscate and Malkavians:
As I've read at the White Wolf-wiki, Obfuscate doesn't really turn your character invisible - it's somewhat similar to a mind-control discipline since it only affects people (and animals, to a certain degree I think, but can't remember that right now) - and not, for example, cameras et cetera.
And since Malkavians are known for their ability to plant illusions in mortal and immortal minds alike, I think the discipline quite fits them. (Besides, since they have it in the P&P game, it's very much unlikely that it'll be taken from them in a new CE release. After all, the game is still Vampire: The Masquerade, right?)
And then just one more short note on your idea of Nosferatu feeding:
Again with the P&P, I can't remember that the Nosferatu would have any feeding limitations. After all, that's the weakness of clan Ventrue.
But I think Nosferatu can gain more blood from rats if they use Animalism Tier 1, although I'm not quite sure that they actually have the discipline... the clan was never one for me, I suck when it comes to sneaking, even with Obfuscate. ^^,