Hello Melissa and Ross.
I hope you have a great experience in Alabama. I've driven hwy 80 some, but not ridden it and it is 4 lane at least until you get to Selma. Take business 80 into Selma and you cross the infamous Edmund Pettus bridge, which is mostly unchanged since the 60s. Of course, hwy 80 from Selma to Montgomery follows the 1965 march for voting rights. It would be a fascinating route to ride by bike. There's markers along the roadside showing where the marchers slept along the way. It took the marchers three weeks to do the entire route.
If you are camping there are several nice Corp of Engineers campgrounds just off 80 between Selma and Montgomery. Prarie Creek campground and Gunter Hill campground are both very nice and are located on hwy 14.
Hwy 80 from Selma to Mississippi is very rural and the terrain is rolling. There are very few convenience stores although I recall quite a few cars and trucks. I honestly don't recall what the shoulders are like.
I wish I could tell you more. Mike Munk would be an authority, but I'm not sure how available he is for questions. Here's his
website. Also, you can check with the
Montgomery Bicycle Club.
Good luck!