Your good at guessing.
The first one is a baneling, a suicide bomber as you say. It's good to burrow them under the battlefield and then explode them while the enemy crosses. D:<
The other one is the infestor, it has three main abilities and can move while burrowed. It can spawn infested Terrans, weak units that is good to use for a distraction in masses. It can use fungal growth, an area of effect attack (not that big of a radius though) that temporarily stuns enemies, detects invisible or burrowed units and deals a little damage.
It can temporarily control a unit with Neural Parasite, it will make itself vulnerable to enemy attacks when it do control the units and it's only temporarily as the connection breaks after around 45 seconds.