Is it possible to connect using the USB cable I was using for the Uno/Mega?
Since the LilyPad lacks headers, is all the wiring supposed to be soldered? Or is there some alternative? (Soldering Irons hate me )
Since each motor is rated at 75mA previously I used a MOSFET to power them on the breadboard, how do I translate the breadboard circuit into something I can mount onto a jacket?
Lastly, I would be very grateful for any general advice or precautions I should be mindful of!
Is the LilyPad capable of communication through I2C?
Since the Lilypad uses an ATmega328P it should be able to act as an I2C slave.
Is it possible to connect using the USB cable I was using for the Uno/Mega?
Not sure what you mean. I don't think the Lilypad includes the USB-to-Serial hardware so you typically use a USB-to-TTL-Serial cable ("FTDI Cable") to upload sketches. The Mega has a USB connector and built-in USB-to-Serial hardware.
Since the LilyPad lacks headers, is all the wiring supposed to be soldered?
I usually see the Lilypad connected with several stitches of conductive thread through the connection holes.
Since each motor is rated at 75mA previously I used a MOSFET to power them on the breadboard, how do I translate the breadboard circuit into something I can mount onto a jacket?
You definitely need some kind of driver to switch 75 mA. The board schematic shows a 33-ohm resistor so maybe it will work on less current.
If you need the higher current, perhaps the ULN2803 darlington array would work. I don't know if anyone makes a lillypad-like board that will hold an 18-pin DIP but you could always design one yourself.
you must make a list of what functionality you need and check if they provide, it's that simple.
Given that the FLora is a later product, it might have learned from 'the working of' the lilypad.