I've never made a tier cake before. I am only going to have two tiers, a 10" round and an 8" round. Both will be two layers. Do I need support rods in the 10"? Also, do I need to put the 8" on a piece of cardboard before placing it on the bottom layer? The bottom will be covered with buttercream and fondant accents, and the top tier will be all fondant. Thanks for any help!

yes and yes

good luck

Exactly what K8 said.

ditto

YES!!!!!!!! Try searching on this site for tips on stacking, there are a ton of helpful threads on here.