To answer your question - No

However depends on the BB. All new BB do not require this and are basicly screwed on. Older models used lockrigns to make sure they would not come loose. Also some models were adjustable so you can adjust the BB to either side.

As you already noticed differnt cranks require different lenght axles.

Now companies make it much easier for consumers. However customizing is a bit harder. I mean buying different lenght axles. Still some older BBs are offered in many different lenghts.