I downloaded cgminer 3.1.1 and compiled it. But it isnt used as default when the pi is starting.
3.1.1 is working with my Block erruptor USB  but only if I start it manually via commandline.

Is there an easy way to automate this and have the stats in the webpage ?

I think the only solution for Block Erruptor USB is 3.1.1 so far..