1. Is WP a good choice for a professional news site?
Yes. It's primarily designed for date-based posting, and that's exactly waht news services are.
2. Are there good themes for news sites? What other things are required?
Probably a heap. It all depends on what you want, what your individual system needs to do, and how much modificaion you are willing to do to the theme to get it to be the way that you want it to be.
3. Do I need to learn PHP?
Not really, but it sure is helpful when you need to make changes!
4. Why WP and not other CMS's like Drupal, Joomla or others?
I would personally say that I find WordPress easier. Other CMS's are still great, but I am not a fan of to many of them.
5. Whay WP and not other specific tools like Newscoop?
Well, what do YOU want to use?
If you don't hav any experience with or idea about CMS systems, teh best idea is to download them all, and try each one out to see ho wwell they fit. There's never one only solution that will work for you. The best thing is to actually look at the system for yourself and evaluate it against what your own personal needs are. Asking questions on here or any other forum is going to get you answers, but most times they will be biased, and have almost no chance of taking into account your requirements because we just don't know them.