I think MMouse is right. With a real engine failure the prop will either be windmilling fully fine or will have stopped and there's nothing you can do about it. For practice leaving the prop at or near max means a slightly poorer gliding performance than moving it to coarse (about 100 ft/min in an Arrow) but at least you won't accidently blow the thing up when you go around! As far as the effect of gear on the glide is concerned - in an Arrow it makes a hell of a difference if you maintain the published glide speed. However, Mr Piper doesn't publish a gear down glide speed which should be considerably lower as Vmd is reduced so knocking 5 or 10 knots off once the gear is down may give you a reasonable glide.