Thanks djemos
I have reinstalled multilib after 455->471.
Meantime I had another solution, but I assume that works similarly as you described. I logged in to LXDE, then I started the skype. It worked without any changing, except the inpu/output levels. I adjusted them (and checked), then I logged out, login to kde471 and skype worked. I could select the audiodevice other than hdmi. Although all settings needed some upgrade.
As a strange phenomenon, then starting firefox (8.0) resulted in kde crash. After reboot everything is fine. I needed to adjust setting again, but that's all. Skype and ff works, no new kde crash.
I am conserving your method also.
Thank you all.