I'm leaning toward D. intermedia but could also be D. anglica

FWIW, here's an old picture with D. intermedia & anglica, side-by-side:

{{gwi:550670}}

So does this particular sundew have to go dormant? If it does, should I just put it outside with my other North American carnivorous plants?

It depends which type of both you have. D. intermedia 'Cuba' & D. anglica 'California X Hawaii' don't do a dormancy, but other varieties of both do. I would lower the temps to ~50 F and the photoperiod as well.