1. Plasma packs don't provide much plasma. I think they fill the thirst bar up about 1/8th to 1/4 of the way. I don't think the plasma fruit is much better. So snacking on Sims seems to be the better option. I am sure this is by design, but I do think that the pack and fruit levels are set too low. I would prefer something like 1/3 to 1/2.
2. There seems to be a hidden sleep need that is independent of the power bar. My vampires are getting exhausted and need sleep even though the power bar is full. Now this is ok, but if this is in fact the case I would like my sleep bar back.