Yeah, definatly banes and lings, medivacs aren't much of a threat but its really good idea to use muta's when u go for that build. U also need alot of banelings don't stop at like 5-10 you ideally u should have 20+ with about the same number of lings. For baneling micro, what you want to do, is normal move through the troops, not attack move, that way they don't target marauders. Plus any that die before they reach their objective still deal the splash damage.
Remember to always keep your muta's mobile, and to watch out for thors. In the opponents base target any add-ons since they die quickly and cut down on terrans production. Also just target whatever you can before they defend. NEVER engage an army of marines with just muta's. Its not cost effective/