Yes, it was intentional, at least planned after they walked into the playground. If you look at it again, the beast was circling them and teasing them. No, I don't think it was anybody who knew Ginger. (That's not indicated at all in the film. And it would have been bigger news that so-and-so was missing. Bigger news than dogs being killed.)
Yes, the smell of blood (and the hormones in the blood) had everything to do with it. You remember the rocking horse reeling and squeaking? The phallic symbol is indicative. The beast is horny for her.
It definitely wanted Ginger as a mate
. It not toys with her, but it wounds her superficially in as many different places as it can. It was making sure she would change, and it ignored Brigitte until it couldn't ignore her anymore.
It's a brilliant scene that moves fast, and you might have missed a few details. One was that Brigitte starts hitting it with her camera, the only weapon she had available. The camera goes off point blank in the beast's eyes. It swipes her and knocks her flying and I mean with her legs in the air.
But she blinded it,
and that was the only reason they got away
. It chases after them, and we hear it howling, probably because it hit a tree or something, but because it's blinded, it runs out in front of Sam's van.
John Fawcett really thought that scene out, and he knew his monster.