What valuable resources we can get out sea water? Shall we next open such company or research laboratory?

Answer 1

This is already being done, and has been for decades.

http://www.britannica.com/eb/article-81292/mining
http://www.goldfever.com/gold_sea.htm
http://query.nytimes.com/gst/abstract.html?res=9506E2DB113BE631A25752C0A9649C946497D6CF
http://www.terrapub.co.jp/e-library/dow/pdf/chap2.pdf
http://www.patentstorm.us/patents/7261912-claims.html