Regarding TextExpander: Smile was so kind to send me an email with instructions.
Open a Finder window.
Hit Shift-Command-G.
Paste in the following: ~/Library/WebKit/
Delete the folder with name com.smileonmymac.textexpander.
Launch TextExpander.
That resolved my issue. (Knock on wood, but no crashes during the last 30 minutes after deleting the mentioned folder.)