The utility I've missed most since migrating from Windows is one called Shortkeys, which makes it easy to define keyboard macros that will insert a block of text in any open application. This makes using canned language to respond to similar inquires very easy.
I've tried using Klipper for this, but found it to be awkward. You want something that sits in the background waiting for any one of a set of sequences, then replaces that sequence with the canned text instantly. You can use an unusual combination like "qq" to start every relevant sequence, to make things easier for the processor.
I've wanted this badly enough that I've considered learning to develop KDE apps to get it, but I'm not sure how hard it would be to implement under Linux/KDE.