@JackANDJude Google will provide you lots of I2C (two-wire) tutorials. sparkfun tutorial is good
and Arduino's API is described here
There are lots of little devices that use I2C to communicate with an MCU, and the protocol allows you to string multiple devices together.
I would be reluctant to solder resistors to the littlebits arduino, because (1) the pads are tiny, (2) the arduino MCU has builtn pull-up resistors that the Wire library enables by default, (3) you could provide resistors on a breadboard for experiments. Typically 4.7K ohm resistors might be used, but the ohm's value required changes if you are stringing several I2C devices together.
using littlebits modules to experiment with arduino-like controllers is expensive. You might look at teensy 2 ($16 pjrc.com) or the classic Arduino UNO to expand your toolbox.
Then you could read about SPI protocol/devices ...
I tested SPI with Sparkfun DS3234 using SPI pins from ICSP on the littlebits arduino.