Yes, Jose Algarin is right. Watching movies or television series is a passive activity. It also takes a lot of time, time that could be spent more productively. Many people rationalize that movies are worthwhile, but I tend to disagree.

Well, If your a begginer yuo can use the subtitles to practice your listening and your reading at the same time you check out the accent and pronunciation, but if you are an intermediate learner it is going to make you to draw back. At any way you only will practice your listening and also you`ll get a lot of vocabulary, is you really want to something that worth to your english skills is practicing with someone else, better would be practicing with a native person.

I tried this and I don't know l enough to work. What I found is a site called Yabla where it has short videos with subtitles in both languages. You can also slow the audio down, pause, go back to previous sentence etc. You can also click any word to translate, download the transcript etc. And they are sorted by difficulty. Once I get better at these I will try again with full movies etc. So I guess it depends on your current level.

Yes it is, it will improve your understanding of the language.