I'm not quite sure if this does you any good or not but here's my .02. I previously owned an 83 1544 Duracraft with a stick-steer set up. I was running a 35 HP Evinrude.
1) Is the "stick" itself easily removable and what determines its length?
The "stick" was easily removable, as it was attached to the cable control box by a set screw.
2) What is the "throw" of the cable back at the motor?
The throw was essentially the same as a conventional set up. Or at least that was my experience.
3) How much mechanical advantage does the stick give you, i.e. are they hard to steer?
They are not hard to steer for small outboards. Steering problems arise by way of the usual suspects, poor maintenance, lube, ect. The only draw back is in order to achieve full rotation of the outboard, the stick has to be almost parallel to the floor. Your seat, or the stick, has to positioned high enough of the deck to achieve this.
4) Is the "dampening" adjustable or do have to have your hand on the stick at all times?
The dampening on the particular model i had was not adjustable. I could take my hand completely off the stick, and it would not pull to one side or the other.
I have found I like the conventional steering better for open lakes and higher powered vessels. But the stick seems easier for small rivers and creeks I've fished. So I guess its a question of how you intend to use it. Whatever you do, don't have ( or purchase) a set up that has the stick and throttle on the same side. My old boat was set up like that but i changed it to put the stick on the port side of the boat and left the throttle in its original position. I hope this answers at least one of your questions.