How does depression/anxiety affect a life? How many people eventually get off the medications?

Depends. Severity varies but depresion and anxiety could consume a person's life. Most people could be taken off medication after a year of remission from a first depression episode.
Many ways. It depends on the severity and duration of the anxiety and/or depression. Typically moderate to severe anxiey and/or depression interferes with a person's ability to function at work, home and with key interpersonal relationships. Many individuals are able to eventually stop taking medications. It is important to engage in healthy lifestyle activities and have a physician monitor medication use.