The green wire actually goes to the cylinder head and its the temperature sensor for either your gauge or idiot light (whichever you are equipped with)
Tubes coming out of both exhaust manifolds are the pluming for the A.I.R. or (Air injection reactor) emissions equipment. The spirally silver/yellow hose in teh first pict is the heat stove connection to the air cleaner to allow for quicker warm-ups.
I'm pretty sure that - yes - you have an O2 sensor, it should be located either near the connection of the drivers side exhaust manifold to the exhaust system or slightly downstream of there.