The motors were scavenged, so I don't have links handy. The big ones are 24V, the small ones 12V, and both are brushed DC motors with a gearbox of some kind; more specific specs escape me at the moment.
The controller in that image is a Sabertooth 2x60 (I also have a Roboteq of some sort), but anything that takes a servo/PWM input will work with the Servo Module. If you want to talk to something fancier that has a serial port, grab a level converter and hook it up to Tessel's UART.
The big red button is an emergency stop. I don't know the part number for that one, but Amazon sells many different kinds. Note that what I did there (wiring the EStop in series with the motor power) should not be done unless the EStop is rated to the motor's stall current.
The little gray connectors (there are actually two kinds in the photo) are made by a company called Wago. The smooth, boxy ones are here and the long skinny one you can't see easily because it's obstructed by a boxy one is here.
Last but not least, I'm pretty sure that wire is at least 16 AWG, if not 14 AWG.