here. In the end, BoVD and BoED agree that preemptive, though not provocatory, strikes against evil are acceptable, and that's what ravages and afflictions are supposed to be used for; softening up a target for kill or capture with minimal harm to the good agents taking action. In the case of capture, it's assumed that the prisoner will be treated with dignity and care, and it's RAW that the ravage or affliction will cease to function if the prisoner has a change of alignment, becoming an ivalid target for the ravage or affliction.
Assassination was never called out as evil. Only the assassin class, which was ultimately a combination of mistake in maintaining internal inconsistency and a legacy hold-over; the assassin class from an earlier edition being tied to a particular evil organization. The only thing evil about the assassin class is a few spells on his list, which aren't necessary for him to fill his designated niche, and the class' alignment restriction. Any Lawful or Any evil, or even Any non-good would've been a more appropriate alignment restriction without either more abilities or more fluff to tie the class to dark forces.
As for those undead you mentioned; if they're the ones I think they are, none of them are actually mindless or of animal intelligence. In anycase, no undead ever -has- to feed. It's right there in libris mortis that an undead will never deanimate for lack of feeding, though they may be rendered completely immobile. Whether you agree with it as a moral point or not, causing harm to living creatures for your own benefit is evil unless it's necessary to sustain your own life. Since undead never need to feed to sustain their unlife it's evil for them to feed unless they have the "victim's" express permission and even with permission it becomes evil if they drain the victim/volunteer to death.