Press releases by their very nature only work well when there is something newsworthy to report. It doesn't have to be for mainstream media (though it would help) but you could target trade magazines / websites relevant to your industry ad perhaps get coverage there.
I don't think press releases work that great for traffic but they can be a good way to get backlinks in terms of SEO.
Press Releases can be good for backlinks, and can be an effective part of any SEO. The task itself can get kind of tedious though.
Press release will work but not instantly and you cannot rely on it as a sole medium. It will work but with it you will have to use other ways also.