Is it possible to cleaninstall and reinstall OS X with a USB boot ?

Sure. I've done it a few times already on some retina MacBooks. This app makes it really simple to set up:
http://diskmakerx.com

 

What would be the advantage compared to an install via the system recovery (and do a clean install from there)?

 

The only technical valid point here is that you don't have to DL the entire OS (I tend to forgot this point because I have fast internet access).

Then, if you prefer to do it this way, it's like I prefer to drink my coffee without sugar, matter of taste, and will not argue this

 

Curious to read details as download from internet basically download the dmg+ scripts to do exactly the same as usb key but from recovery partition...

Urban legend I guess?

 

I don't have an answer to your question, but I would like to point out that installing from the recovery partition is not the same as internet recovery. The OS installer is on your harddrive already so it would actually be faster than booting from external USB.

 

Yes, I've done it.

Download the Yosemite installer. If done now, it will be 10.10.3 which is the minimum version you need. Let it download but quit the installer when it starts to run. Use a formatted USB stick at least 8GB minimum. Then run these commands in the terminal window:

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

Note this assumes the USB stick is named Untitled. This will take about 20 minutes. When complete restart and hold the option key. Select the USB stick as the startup. Then after the you boot to the installation window, select Disk Utility from the menubar at the top. You can then then format or erase the SSD. Then quit Disk Utility and run the installer on your cleaned out SSD.

I do this for almost all new Macs and I get and I did this for the rMB.