Playing with the board ! We have done some progress here =) You can see on the right side the SMA for the transducer, the green connectors for the motor, and the RECOM on the bottom.

There was a short-circuit between 5V and GND, documenting it on GitHub, with images =)

That being said, there was a short article on ultrasounds, interesting read at http://www.maori.geek.nz/why-are-ultrasound-machines-so-expensive/ and on the corresponding thread on HNews (130 comments so far!). It focuses on the piezo, but raises some questions as well.