esanger, I'll try to give a brief non-tech answer.

Stall: commonly, the point when forward motion is slowed enough that the plane wants to fall out of the air. This point will vary with the same plane depending on how it is set up and the angle of the wing to flight path.

Washout: take a peace of paper and hold it up so you are looking at one end. Now imagine that the end furtherest from you is attached to the plane at the fuse. Now imagine that the left end of paper closest to you is the rear of the wingtip. Bend just the left end of the paper up. That would be washout. If you bend it down that would be wash in. The thinking behind this is the center of the wing would STALL first allowing the plane to kinda mush forward instead of STALLING at a wingtip causing the plane to drop to the side. The bad side is that when flying inverted you have just the opposite.

Incidence: If you were to draw a straight line down the side of the plane and compare the angle of the rear stab, wing and engine to it you would have the incidence. I use the rear stab as 0 degree. If the front of the wing is higher in relation to the line (and the rear of the wing lower) then it is said to have positive incidence. If the centerline of the engine is up at the prop end then it is said to have upthrust. If viewed from above it can also have right or left thrust.

Maybe by moving this back up to the top of the threads someone who has had more sleep than me will jump in with a better answer. Hope this helps.
Ed M.