That vampires can't enter a house without information is a long-established - if mostly forgotten - tradition. You've never watched Buffy the Vampire Slayer, I take it?

Anyway, the whole Dracula thing; Lucy sleepwalks. The first time he sucks her blood, Lucy actually sleep-walks out of her room and into a cemetery. Later she is seen to have an unconscious desire for the vampire to enter - as seen in the way she pulls the garlic away from her neck while she's sleeping. The garlic was only placed in the room AFTER Lucy had unconsciously invited the vampire in to drink her blood. After a vampire gets permission once he can enter at will.

As to why vampires would actually be invited into a house, there are several reasons. In Lucy, the invitation was unconscious and she didn't realize that she had issued it. Renfield, later in the book, was tempted to open a window with promises of riches and happiness. In a more modern example, Buffy's mother in BtVS invites a vampire in because she doesn't realize that the vampire is a vampire - in fact she doesn't know vampires exist at all. Similarly Buffy invites Angel in because she doesn't realize he's a vampire.

Re: sparkling vampires: "THIS IS THE SKIN OF A KILLAH!!!!" *sparkle sparkle sparkle* Ah... No.

Vampires traditionally burst into flame because sun = truth and vampires = demonic creatures who cannot abide truth. In many works of fiction, however, vampires are not immediately killed by sunlight, or are merely hampered by it. For example, vampires in Skulduggery Pleasant (good book by the way, you should look into it) are for all intents and purposes weak, blind humans during the day, only transforming into fearsome monsters after the sun goes down.

Dracula was a vampire. He drinks blood, turns Lucy into a vampire, turns into a bat and into a wolf, is repulsed by holy water, garlic, and silver, crosses especially. He has no reflection and cannot go out in the sun. He's a vampire. The entire book, however, was a metaphor for Stoker's habit of going out at night, leaving his sick wife at home. He viewed himself as a sort of vampire and wrote a book about it.

Twilight vampries (meyerpires) are not vampires, they are fairies pretending to be vampires pretending to be humans. They break every rule of vampirism ever made.

USUALLY, vampires are evil creatures that survive on human blood. They are vulnerable to sunlight, garlic, silver, crosses, holy water, etc.

There are many types of vampires. There are the suave, pale vampires like Dracula. Others, like Nosferatu, are hideous monsters. Some are large, bloated red leech-like things. And some vampires are indistinguishable from humans until the feed is upon them, in which case they appear demonic. 

DRACULA. I read it first when I was 11 and then again this year and it was wonderful both times. It has a lot of traditional vampiric lore and a suspenseful story line. Also, I can't see your parents objecting to it because it's a lot better than some of the junk you could be reading instead.

As to more modern material... There's a series called the Chronicles of Vladmir Tod about a 13-year-old non-traditional Dhampir (half-vampire) which is pretty good and a quick read. The books are Eighth Grade Bites and Ninth Grade Slays, so far.

And now I'm drawing a blank.