KDE doesn't seem to have a way to customise the text cursor blink rate, or to turn off blinking entirely. In GNOME and Windows, this is customisable through their accessibility features. Not sure if this belongs in KWin or somewhere else? Sorry if I've reported against the wrong component.
This would have to be done in Breeze; moving there.
This looks like a dulicate of bug 343635, although this applies to Breeze and the other to frameworks.
Indeed you're right. Note that in addition to allowing it to be explicitly customized, we should also make it respect the systemwide animation speed setting by default. *** This bug has been marked as a duplicate of bug 343635 ***