Cross ties indoors where there are three walls surrouding the horse are OK. That having been said, cross ties outdoors are VERY dangerous with a flighty horse. Something could come up and spook him, and he'd have nowhere to go. Also, in my opinion, cross ties should always have panic snaps. They look like this: http://www.ldsleather.com/images/panicsnaps_556x341.jpg
and can be purchased at a local feed store. If need be they can be attatched to another snap. I boarded for a while at a barn that had regular snaps, and I'd just snap those to the panic snaps, and then snap the panic snap to the halter. Panic snaps are designed so that a quick jerk can undo it even when it's under tension, while other snaps require slack to undo.
A panic knot is a good start, but with a flighty horse I'd still recommend a nylon halter and lead rope with panic snap at the end of the lead rope. Even good knots can take a moment with a really tight lead on a panicked horse, and sometimes that's all it takes to be in really big trouble.
One problem with a horizontal bar hitching post is that the lead rope can slide back and forth as the horse paces. You might try attatching a metal ring to the wood, and then tying the lead rope to the ring. With a panic snap on the halter, it wouldn't matter if the rope got stuck in the loop.
As far as the actual behavioral aspect of it, that depends upon whether your horse is scared or pacing due to impatience. I haven't seen him so I couldn't tell you. Is he pacing back in forth in a repeated pattern, or jumping quickly when something moves or changes? If he is being impatient and disobedient, a sharp smack on the neck, chest or rear is appropriate, but never on the head. If he is frightened, a reassuring, calming hand and low voice is in order. How old is he,and what kind of past does he have? Do you know of any bad experiences he's had? In general, when horses are frightened punishment will only worsen the problem. It's like hitting a child that is scared because someone has just jumped in front of it with a mask. If he's scared lay your hand at the point where his neck joins his shoulders and talk to him in a low, reassuring voice. Also try rubbing his withers.
Hope that this helps, and hasn't confused you more.