It's not only the YA life stage that is lengthened -- Adult too. And you've got your numbers wrong, it's 104 days each. By each, I mean that Vampires have 104 days in YA and another 104 in Adult.
What Simstar and MoMoll said is perfectly right.
There is also a snack called Plasma Fruit Chowder, available only in Bridgeport, via Food Trucks. Vampires don't get sick when they eat this, too.
One thing that is worth a note is that born vampires skill at a much faster rate than the ones who get turned. This is also an obvious glitch. Each time you open a save file that has a
born vampire in it, the worse it gets. Vampires were meant to skill only twice as fast as normal Sims, but not at such a rapid rate. I got this info from the official forums.
The skill modifier is broken. Every time you reload the game, vampires skill faster. Some skills are instant 1-10, like photography. Eventually, your normal non-vamp sims will stop being able to skill because of this.
For the very few that actually have had it where your sims cannot skill, this is the problem.
Edit: I know that they are supposed to skill faster, but it's supposed to be 3x not 100x.
Leto, do you need the exact names of moodlets and interactions as well? Because I can provide those, too.