Currently in the manga series, hunter x hunter is in chapter 290 and is on hiatus. It is hard to predict when it will be out the manga or the new season, since (as the news say) Yoshihiro Togashi is...
Nope, and at this point, the chances are slim.
The Ryodan/Spiders (the same thing) Some people say it is Hisoka but he just wants a good fight with Gon
I don't really understand what you said about "hunter x hunter piano" but there is a piano version of "Ohayou". (hunter x hunter opening)
Yes, Viz Media dubbed the whole series. However, the three OVA were never licensed or dubbed.