Different for each job but average screening process to understand past work history. They also asked me to walk through relevant work samples to better understand the experience I bring to the table.

I interviewed with one of the companies registered at UpWork. You search for a jobs that you are interested in and relevant with your skills. Then you show interest in the company. If the employer thinks you are a good match, you will go into an interview process.

Nothing really. Just had to wait a month to be accepted. After that it was up to me to send in proposals and wait to be accepted for a job