Some software languages or platforms are easier to do TDD in than say proprietary computing "appliances" in proprietary languages. You've mentioned Python, which is a pretty flexible language and conducive to doing TDD. Do you do most of your project work in Python?

You mentioned getting bug fix requests. How many times over the year do requests like this interrupt your other project work? On average, how much of your effort does servicing such requests (research, meet over them, plan a fix, then do the agreed upon fix and test the agreed upon fix, deploy the fix) take? Hours, days,...?