I have managed to install all WA extensions in Dreamweaver CC today through the Extension Manager. However, they all took ages. I'm running Windows 8 64 bit. It took several hours to install all of them and at times it looked like nothing was going on, but I just left it and eventually each one installed. My advice is to give a LONG time to finish installing each extension. Hopefully WA will have fixes for these issues soon - don't fancy waiting 2 hours per extension uninstall/reinstall for future updates.