According to Longman Dictionary of Contemporary English
Select is more formal than choose, and in everyday English, people usually say choose rather than select.
According to Merriam-Webster
choose: to have a preference for or to select freely and after consideration
select: to choose (as by fitness or excellence) from a number or group
In practice, choose and select can be used interchangeably.
if something is customary, it is what people usually do in a particular place or situation
Synonym => usual
Is it customary to tip hairdressers in this country?
typical of a particular person
She arranged everything with her customary efficiency
traditional => being part of the beliefs, customs or way of life of a particular group of people, thathave not changed for a long time
It's traditional in America to eat turkey on Thanksgiving Day.
2 (sometimes disapproving)
following older methods and ideas rather than modern or different ones
traditional methods of teaching
The main difference between "customary" and "traditional" is timing. If you do something in a customary way for a very long, long time, it will become "traditional".