Boot loading a blank STM32 chip with Espruino on a custom made PCB

Hi guys

I've been working on prototypes that involve me making PCB's and using Arduino/c as the software that runs my applications.

I've recently been looking into Espruino and would love to writing javascript than arduino on my micro controllers, however this will bring up the following challenges - if anyone can help answer these I'd really appreciate it:

• What are the schematics/pcb layout of an Espruino Pico?
  
• How does one bootload a blank STM32 chip, (I've found this link http://bit.ly/2kWdqPy, but there are no images/videos to give clarity to what is being said, are there any other links I can look at?)
  
• Are there any major differences in bootloading/working with STM32 chips compared to ATMEGA's?
  
• Is there any general advice that any one can give me on this topic that I may have overlooked?
  
  

Best
James