Yes, lower Abrams has smallmouth, and a NC license is good as long as you're in the park. It's a good hike down there, though, (the smallmouth are below Abrams Falls,)and there are a lot of other places with better populations of smallmouth that are a lot easier to get to. With all the fly fishing for trout that goes on here, river smallmouth seem to get ignored sometimes, but they are one of my favorite fish to catch. River smallies don't get as big as the ones in the lakes, but it doesn't take a big one to bend a fly rod and put up a good fight. And in most rivers, you can catch small ones one after another.
Almost any sizable creek or river in western NC has some smallmouth in it, including the lower reaches of most trout streams. The Little T, Tuckaseegee, French Broad, and Pigeon are all good smallmouth rivers. For numbers, it's really hard to beat the French Broad below Asheville. And you might tie into a musky, to boot.
In the GSMNP, besides Abrams, the lower Little River and Oconoluftee have smallmouth too, as do the lower ends of Cataloochee, Hazel, Eagle, and most of the other bigger streams. But they are scattered among the trout, and aren't always easy to get to. The rivers listed above are better options.
Most of the river smallmouth run from 7"=8" up to a foot long and a pound or two with an occasional 3-pounder or bigger. The big ones are few and far between though, and you will catch a ton of the dinks. Here is a typical solid river smallmouth at the upper end of the common size range:
3smallie3 by
Yaller Hammer, on Flickr