I've received few of the components (except DC converters) and started assembling the board. 

It is alive!!!

There are few mistakes to take in count for future version:

1) GND vias are not linked to GND net

2) Few footprints are a bit small for hand soldering, it could have been a bit bigger

What I still want to do :

1) create a programming rig with pogo pins

2) create a test jig that can perform tests on devices for several hours

(I want to do this for fun and learn, it is of course overkill for this project ;) )