I'm sorry, I gave way too many suggestions for that short amount of time. There will not be enough time to drive to Dillard, Highlands, Tallulah Gorge, etc...
My suggestion is to spend some quality time hiking to Anna Ruby (the pathway from the parking lot to the base of the falls makes for a nice walk) and some of the trails right there at Unicoi. The trail loop around the lake is a nice, scenic walk and easy to access from the cabins. It is worth your time to walk around Helen, but it is probably going to be too cold to float the river and I doubt they are doing that right now anyway.
As for bears, if bears were eating tourists, that would not be a good thing for tourist promotion so they try to keep that part quiet.
My best suggestion would be to not try to do so much, take a few hikes, enjoy Helen, visit the mill and Betty's and enjoy the cabin and cooking out. Don't feed the bears or the locals and, this is my best advice...if you kinda like here, then just plan to come back when you can stay longer and do more. You might not even like this whole area, and if not, you have not wasted a lot of time. Quite, peaceful, outdoor pursuits in the mountains are not for everyone. If you find you have time for one side trip, I would go with Tallulah Gorge. It is a beautiful area.
One warning, local news reports there are bigger crowds than usual right now because people are getting back out after being home for so long. So you have a mix of locals, city dwellers from Atlanta, and tourists from Ohio all competing for the same trails space and waterfalls views. Of course, some might get chased away by bears!