Attached Link: http://www.e-onsoftware.com/Download/Vue4InternationalResources.php

Joerg, please download and install the English resources from the above link. This will fix problems 1 & 2.

Re problem 3: does that happen all the time (with all materials), or only with specific material and/or scene combinations?

"...it seems to me, that the original 4.0-texture-editor was more stable": does that mean the material editor actually crashes often in Vue 4.03 on your computer?