Your setup really depends. If you think you know the direction they will come, then face that way. Their eyesight is poor and it's dark so being relatively in the open doesn't hurt much. I've found that they'll work field edges just like deer, so use that to your advantage.

As far as the post-hole... I dig it in an area that a full moon will shine on, but very near cover. They don't like to come way out into the open, but 20 or 30 yards is fine.

If you happen to hunt a full moon and have a good scope (like my Nikon Monarch 3-9x40), there is plenty of light without a spotlight. Be sure to turn your scope to 3, so that you get the most light to your eye.

For timing, I'll get out there about 30 minutes before dark and then hunt until I'm tired. 10 or 11 is usually all I do, since I have a 2 or 3 hour drive home after. From my deer hunting trips, I can say that they work just after dark until a little after daylight. The hole with corn seems to make them come in earlier, though. I'm wanting to try an early morning hunt (3 AM to daylight), but I haven't done it yet.