I have a few questions that I haven't been able to find out on my own.

The first is regarding Pureblooded vampires. When they attack and infect someone do they become normal vampires or vampire lords?
I'm just very confused as to why there are so few vampire lords vs normal you would think more people would be lords than regular.

Also are deathhounds and gargoyles daedra or normal creatures?

and my final question wouldn't biting someone infect them? why is we feed on people when they sleep yet nothing of note happens to them.

I believe they would become Vampire Lords as Serana/Harkon's bite makes you one.

As for Gargoyles and Deathounds.. that's a good question. I'd venture to say they are probably related to Bal.

That's actually a common trope with Vampires in general.

The difference between "feeding" and "turning" someone seems to be based on intent. The Vampire in question can somehow control it

Feeding is blood in, turning is blood out.

I assume that the Death Hounds are http://images5.fanpop.com/image/quiz/778000/778473_1327191883195_327_300.png, and that the Gargoyles, as we can see from Valerica's half-finished Gargoyles, are clearly actually crafted from stone and brought to life, somehow. I like to think that they're simply enchanted, and that the particular enchantment is a lost magickal technique.