Seem to be quiet and secluded, kind of like those geeks you see hidden in the library at school. Now its not because they hate themselves, but many and most vampires have been around for quite some time, and know a lot, so they are geeks in a way. they have vast knowledge many come to seek. Some have manors, others to not. the "younger" generations could give a crap about the knowledge they hold and would must rather seduce and take advantage of their young age and dashing good looks. Yes, the vampires do feed on blood, yes they can feed on animal blood, but when doing so they are not going to be able to reach their full potential because it's the human blood that allows their reflexes to be as sharp and fast. Though they will have their normal heightened senses, abnormally strong skin and being impervious to most injury, those that drink animal blood can very easily get stabbed and be wounded, but that certainly won't kill them. Unlike their "wolf" cousins these creatures can very easily live long solitary lives, having no real need to be with someone for the rest of eternity, but there are the young ones, who will always want to be normal and live a single life. As the generations become younger and younger their out looks on life seem to become dimmer and dimmer.
Yes, vampires are immortal and are technically the "undead". Their hearts don't beat, the don't age and will never die from illness, injury or hunger.
Blood lust would be a major weakness for these creatures. If they do not feed on a regular basis to make that hunger sleep they will go into a rage and feed on anything they can get their hands on, even if they only feed on animals they will go into that rage and feed on humans. Also, if bitten by a werewolf, and the syliva enters the body it will cause the vampire to age to their true age and then die. It has something to do with the compound that changes humans into wolves. It kills vampires. UV light will also burn and seer the skin of a vampire, to much exposure will turn them to ash.