Crawdad is the term of the Arkansas masses or the casual name for them. Crawfish is a bit more formal but universally understood and is the term dictated for newspaper usage by the Associated Press Stylebook. Crayfish is preferred by scientists. And, no, the distinctions aren't on a north-south basis like some other of our wildlife terms.
In Arkansas, crawfish are all around us, available for most anyone who will get out and hunt for them, work a little. Catch a few, and you've got the makings of a fishing outing that ought to be successful, if you otherwise are halfway competent in angling.
Bream, bass, catfish and trout all go for crawfish or parts of crawfish. Probably, crappie will eat them too, although they're not a normal crappie bait.
You'll find crawfish for sale in bait shops across Arkansas, but this availability is spotty. A phone call or two could save some frustration.
Some Arkansans have the opinion of small crawfish for fishing, larger ones for eating. The little ones can be used whole by slipping a hook under and through a section of the shell and tossing it into the water. The crawfish will supply natural movement on the bottom of the water, drawing attention from fish.
If you can find a shallow stream with a rocky bed, you've got a likely spot for getting enough crawfish for fishing use. Turn rocks over and move quickly to grab them. Keep them wet and as cool as possible. If you can locate a farm pond being drained, that's a potential major crawfish supplier.