So I spoke with my DM and we've decided to forego the vampiric heritage for now. Turns out we're leveling up in time for tonight's session, and although he had many of the same ideas and suggestions as everyone here, we've both decided that it's just a clunky thing. I want to keep the longspear; using an action point for this blood drain power isn't economical (and I was reminded that I'd only get to do that once every two encounters!), and I would need to invest a lot just to make it workable.
And, the main reason I wanted to do this was so I had something to explain my character's background, and add some flavour. Which is nice, but it's a lot of work for just that. So I'll hold off until it's a bit simpler--perhaps when I can get my hands on a grasping longspear.
In the meantime, I can acheive the same ends through roleplaying; I've decided that every once in a while in combat, my character will simply lick the blood off her spear (or wipe blood onto her hands and lick her fingers). Still creepy, still vampir-ish, and it won't tie up gameplay options and feat choices. Plus it gives me some precedence in case I want to take the vampiric heritage feat down the line (which I do, as I've found the Bloodknight pp, and definately want to go that route...)
But all of this makes me think...what exactly is the intent of this power? Is there an optimal solution, perhaps with a different race or class, that doesn't make it so difficult to use easily? It seems cumbersome.
And thanks everyone for being so helpful...even if i didn't take this route, I've learned a lot about mechanics and economics with my actions, and it's been very helpful. Most of all, I'm starting to see the value of roleplay vs mechanical play--that is, sacrificing mechanics for a good character concept isn't necessary, and it's best to find something that's efficient (and roleplay around it) than to get some concept that's hard to play, but cool.