Q: nedd a diagram on 1990 Chevrolet Lumina

Okay I was driving and I notice that my van didn't have oil as I was driving the van shut down and it was smoking and oil leaked out the bottom of it. Is that a real sign of damage? Or can I put oil in it and still be able to drive it after the fact.

It Idles little high and while sitting at a stoplight the Idle goes low and lower and then engine turns off.

My turn signals don't work unless I hold the lever up or passenger side and down and push forward or drivers side, The mechanic wants to chage $120 or labor to put the new switch in, is that an appropriate amount to charge?