Cold start engine speed / idle speed / etc

[johna]

When the engine is started from cold it should automatically run at a little over 1,000 rpm for a few moments before settling down to normal idle speed... right?

And when you come to a stop the idle speed should stay at around 1,000rpm for a few seconds before resuming normal idle speed... right?

My car occasionally does these things but rarely. My question is what controls these features and why aren't they working all the time? Should they be?