Thus far, the coldest that it has been during one of my runs was 49 degrees and I was fine wearing a long sleeve rD top and shorts. Running in the 30s is a foreign animal to me and it's not something that I can simulate in the next 1 1/2 weeks. The thing that is somewhat freaking me out is "nothing new on race day." I've never run wearing gloves or a winter hat before, so I don't know what the hell is going to happen during the HM.
I'm hoping beyond hope that your attitude will bring with it a change in the temperature forecast. At least into the high 40s or low 50s. I still won't be comfortable, but it's doable.
FL 30s is tough as the humidity can be more bone-chilling cold than say MN 30s. Gloves should be fine at that temp, I prefer a fleece glove compared to the cheapie $1 gloves, because the elastic on the wrist bothers me and makes my fingers numb. Something like this:
For hat, I recommend a fleece headband. Nothing too tight, shouldn't cause any issues.
Agree that the "nothing new" rule doesn't really apply to headband/gloves unless you have fabric allergies or something, either case I always recommend washing before wearing if possible.
I would definitely be wearing pants if it's truly going to be in the 30s. In MN I will actually wear fleece leggings at that temp, because it's hard to move with cold/stiff legs. If you haven't worn pants before on a run, I'd probably consider getting a pair now and testing them out to make sure they don't fall down. I have not really had issues with chafing related to wearing leggings, but certainly have had issues with them not fitting right and falling down. A belt like a flipbelt can be great for keeping pants up though, in desperate times
For tops, just layer more. In the 30s, I am probably wearing at least a long sleeve + quarter zip, and often will add another short sleeve or thicker quarter zip (such as a fleece Columbia) if there's wind.
A neck gaiter is another great thing to have. I'm partial to the brand Buff. 30s is a bit of an iffy temp for me. Most of the time I will be fine with a regular buff (coolnet UV) but if the windchill is bad, I will switch to a lightweight merino wool buff. I find the merino wool better for breathability if you need to cover your mouth/nose with it (I can't breathe through normal version).
. My run this morning had a temp of 72 and dew point of 68. I thought I might melt into the ground! 
. I am planning to buy a pair of gloves though because I only packed one pair and they're the ones I usually wear for winter running.
