I got back to trains last year and used Tortoise machines, having years before used Atlas undertable machines. I really like the Tortoise.
a) here is where you can click to get an instruction sheet
http://circuitron.com/index_files/Tortoise.htm
b) the Tortoise has eight contacts. Numbers 1 & 8 are for DC power, which you reverse to change the turnout direction. The DC can be provided by an item like the Circuitron power supply for this purpose. Most people use a 2-position (no center off) DPDT switch for each Tortoise to do the switching. I believe the Tortoise instructions show how to wire the DPDT. There is also an old thread here somewhere, with diagrams, maybe we can find it. EDIT: see the diagrams (particularly the one from Rich) in the following thread:
http://cs.trains.com/mrr/f/744/p/214769/2358228.aspx#2358228
The Circuitron supply will handle up to 30 Tortoises (wired in parallel through their respective DPDTs) if I recall correctly. They always get power; the current varies to each depending on whether the Tortoise is moving or “stalled” at the targeted direction (finished moving).
c) The Tortoise is usually mounted under the table, first drilling a 1/4" or larger (I used 3/8") hole under the throwbar. A wire is attached to the Tortoise and works as a lever to move the throwbar. The wire also holds the throwbar with spring tension in the desired direction. I used 3M double sided tape to temporarily mount it (threading the throw wire up into the throwbar hole) and when satisfied, added a couple of screws.
d) Auxiliary contacts (there are 2 sets) on the Tortoise can be used to power the frogs if you like, or to swich signal lights, etc. But that is optional and separate from the t