1995 Accord: Speedometer/gear indicator/hesitant acceleration.

I know nothing about cars, and I have no business under a hood; this post will prove my point. LOL! I have a 1995 Honda Accord EX. Background: I left the oil cap off one day after I added oil, and oil flowed out into the engine compartment. The oil gunked up my hood latch, so I took some WD40 to loosen it up because the latch wasn't locking the hood shut. At the same time I took some WD40 and cleaned some of the oil grime off the head of the engine block. I may have gotten some WD40 around the spark plugs/cables. I'm not sure if this is relevant to my problem I'm about to list, but this happened this morning before the problems came up, and before that my car was running perfectly with the exception of decreased gas mileage (for about 4 weeks now). Problem: Now, as I accelerate, 1) the car hesitates, but when in park the engine sounds ok and doesn't want to turn off, 2) the speedometer either fluctuates rapidly as I steadily accelerate, or it stays at zero (while the car is in motion) or while in park and I rev the engine, it fluctuates up and down with the tachometer, 3) the light on the dash that indicates what gear you're in (i.e. D4) blinks consistently, and 4) finally the check engine light came on. It was suggested that I let the engine dry out in the sun with the hood open to see if any of the WD40 over spray would dry out, and that's the poiint I'm at right now. What could I have happened? What could be some outcomes?