The STM32L476 discovery board has a useful built-in USB/Serial emulator in the ST-Link debug interface. This allows you to exchange data with the board without any extra hardware. Sample code is over here.
I have begun working the STM32L476 Discovery board taking a “Bare metal” approach. It is a great board with some nice peripherals. Code will be built up over time over here
To compile this code you need the a cross compiler for ARM that works on your system. You don’t need a fancy debugger or complicated software : the board has an mbed interface so you can just copy the program you develop to the board as if it was a removable disk.