Could anybody advise me. Is it possible to use Sony HVL-IRH2 videolight or Sony ECM-HS1 microfon attached to the accesory-shoe on top of the XL2?
I will not try this before I'm absolute sure that nothing will be destroyed!

- Per Johan

Sony and Canon have different pin-out arrangements for their respective hotshoe accessories. I can pretty much guarantee you that they're NOT compatible.