According to her, human emotions entrance them so much it's like a drug, and

"that's why they built portals into our world, that's why they entice us in."

She added that Aes Sedai delighted them especially for some reason, and had she known she could have added ta'veren, from their reaction when they get Mat's eye:

""The savor!" one Eelfinn exclaimed.
"So long!" cried another.
"How it twists around him!" said the one who had taken his eye. "How it spins!
Scents of blood in the air! And the gambler becomes the center of all! I can taste fate itself!"

A bit late in the game for disinformation, I'd say, especially when all Birgitte said on those matters is corroborated by what happened to Moiraine and what Mat experiences at Ghenjei.

The price of the Eelfinn always seems to be a "blood price", a small piece of Mat's body drives them nuts. The Aelfinn "feed off" emotions as well, but they don't seem to need any physical interaction, so they don't even ask a price, they simply take what they want from you.

As we see in TOM, the Eelfinn too seem able to "see" Mat's place in the Pattern, the Pattern which of course is woven of saidin and saidar. They see it "spin around" Mat (which goes hand in hand with another theory of mine that Spirit is a flow produced by the souls of sentient beings in the human world, and apparently in Sindhol, but not in the Ogier world)

And in the part of the (post TOM) conversation with Brandon you didn't quote, he RAFOed where their ter'angreal come from, and makes the same comment I do that it's one heck of a coincidence they have the exact ter'angreal to fit a demand...

"Matt: Really? Heh, so the obvious question, where did the 'Finns get great stores of ter’angreal, angreal, and is that part of the Pact they made?
Brandon: RAFO…but if you just think about it, we don’t even have to go to the notes for this if you think about it logically, we know of them providing certain items of Power to certain individuals that they were able to match very nicely with certain requests very easily. If you run the statistics on that, it's either a huge coincidence or they have very many to choose from"

Rand (LTT) is likely to shed some light on that. Or the encyclopedia will, as Brandon said it would be full of revealing material on matters left unresolved in the books.