Here are my thoughts.
I agree the Vamps should have Human fodder. I suggest that they should always have the ability to build one or two low level units. For the sake of human players, the Vamps should have that thirst promotion that A_H mentioned. But gettin the AI to understand it might suck. The bulk of the Vamp armies should be cannon fodder imo. (As we all know, the AI will make it almost all cannon fodder. AI doesn't like to upgrade. WIMPS!)
Question. Are the Counts the only units that can be Vampires? Or can they pass it on to other units? (Although, I think for simplicity's sake that we should go with wat I say below. It eliminates the whole 'which unit do I pass vampirism onto' thing.)
I think that there should be a UU added much like the Calabim Vampire in FfH. But Sylvania should only be able to build five of them. That would fill out the minor nobility of Sylvania and not make it so jus the Counts themselves are the only Vampires.
The permanent war thing I disagree with. I think that the evil civs havin the large negatives towards the good and visaversa would work better. One thing to point out tho, when I play as the DEs, the HEs have a positive for our shared religion. This makes no sense, as the DE mainly worship Khaine and certain aspects of the other Chaos gods. And, of course, the HEs worship Isha and Kurnous. So, I think that between the DEs and HEs that positive should be removed. (Of course, that positive also is present with the WEs and should be removed for the same reasons.)