ABS seems best between 195C and 205C (can depend on the manufacturer, the colour pigment, even the batch) and the bed may like being a little hotter than the default but it's more a 'what works best for you' situation.

I run mine at 115C but I've been told that's probably a bit too hot and I'll get better overall bed temps if I run it cooler. (I'm yet to test)

Its ALL completely unnecessary on the Solidoodle 3 with the new motherboard... I can't say for the other ones.

Just edit the G-Code (save, notepad) and add '@pause' to pause the print, and do the rest manually.

Typically I"ll find a line that has a Z-change to the layer I want to change at, for example, I'm printing at .3 mm and I want to change at layer 5, so I search for Z1.5, and add this before that line:
----- something something E0   (stops extruder)
G1 Z50.000
@pause
------something like G1 Z1.500

Then save your code, and reload the G-code and it'll do a head raise and a pause for you. Then retract the old filament, and extrude in a new color.

Also, The Solidoodle 3 with the new motherboard uses completely different temperature settings. The temperature sensors are calibrated differently and apparently one(or both?) of them does not reflect the actual temperature. The defaults in Repetier host or the documentation did not work! Initially it wouldn't stick, So I added a glass bed using hairspray, and that it would stick for an hour or so before it would curl and the curling would ruin the rest of the print. So, for the new model ONLY, use Extruder=215 and Bed =110. I found this out today (after a very frustrated email to support), and the print appears to be doing better so far... This caused me two months of agony, hopefully I can save someone else the trouble.

I'm familiar with GCode, and I really like the way that multicolor printing works!

However, the only way I can get the filament to change is to manually press the pause button and retract the Z as fast as possible. This works, but required me to hover over the darn thing until its at the right point.

What I really want is to put this operation into the G-Code, where the machine would retract to the home position, and then pause, with a message indicating what color to change to...

Going through the Gcodes listed here, I found the M600 to be what I want:

M600 - Pause for filament change X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal

But Placing the ol' M600 in there does Jack and Squat. Why isn't my M-Code getting recognized?

When I type it into the G-Code Editor, and click on the help, it does not have a description for M600. Do I need a firmware update or something?

I've also tried the M226 shown on the RepRap page but it doesn't work either!

What gives???