Not traditional. Mainly relies on your relationship with the professor. Basically you just want to email your professor that you are interested in TAing for. They will most likely respond if you were engaged in their class, tried hard, and had a decent grade
Not complicated process, all you need is to find a class and a professor you would like to work with and they will recommend you for the job. No interview needed most of the times.
The job interview process does not exist. All you need to do is just submit the graduate admission and you will automatically be considered for the job. That is all I know.