I am under the impression that "dann" and "sodann" both mean "then." Is there any type of difference in their meaning or usage?
dann is more versatile, You cannot replace it with sodann everywhere. E.g.
dann is also then in the sense of if .., then .. else.. (wenn, dann)
Also in questions
wenn nicht hier, wo dann? - If not here, where else?
temporal point in the future
wenn es dann immer noch regnet - If it is still raining at that point
sodann can always be replaced by dann, however.
1) temporal ordering (then, followed by)
Ich tat dies und dann jenes. - I did this and then that. Ich tat zuerst dies, sodann jenes.
zur Grundausstattung gehört sodann ein Klappmesser - The basic kit also contains a knife
In general, you will not hear sodann very often. I know it more from older texts rather than spoken language.