Okay, I've tried to reply twice now, and something's glitchy on my end. If this post shows up 3x, my apologies!
I'm in a SC beach town, and I see a lot of sheath dresses with cardigans or blazers here, so that would be my vote. If you want a full suit though, have you tried eBay? I've tried on enough suits at the local brick and mortar stores that I know that Banana Republic, Ann Taylor, and Ann Taylor LOFT size "x" always fit me well, so periodically I'll do an eBay search for those brands in my size. I've scored two LOFT suits for $40 each, a NWT LOFT suit for $100, and a NWT Ann Taylor sheath dress for $40 that way. Also, if you have any outlet stores nearby, I can usually find Banana Republic and Ann Taylor suits for around $125 there. And Banana Republic is having an online sale, 30% off right now. I saw a black a-line skirt suit for about $140, although that's probably a bit too formal for your needs.
I would suggest a skirt over pants, just for the interview stage. At least where I am, there are still some interviewers that are less likely to hire a woman in a pants suit, and right or wrong, I like to stack the odds in my favor.
As a curly girl myself, I don't think a blowout is necessary, but just bear in mind that southern humidity may make your curls more prone to frizz. I use a flat-iron if my hair just won't behave, but I've never bothered to have my hair professionally straightened. If I don't have time to flat-iron, I have some clips and hair slides, and I'll pull the whole mess into a pony at the nape of my neck, and smooth the frizzies with hairspray.