Guess it depends on what you mean by "many." ;)

Besides the heroes of Vibora Bay, there are superhero teams in Houston (The Hero Corps, five members), and Miami (The Watch, five members), plus solo heroes in Houston, Atlanta, and New Orleans. These are only the heroes mentioned by name in Champions Universe Sixth Edition; there may very well be more. And of course there are plenty more named in other parts of the US.

Whatever happened to Nighthawk?

I know why and how he left the champions, it's just where he head off to?

Nighthawk founded his own covert superteam, dubbed Project Mongoose, specifically to hunt and harass VIPER. Most of its members are heroes or "grey" villains who have particular enmity against VIPER, like Nighthawk himself.

If we're getting a grittier section of MC coming soon, I would not be surprised to see Nighthawk appear in game. ;) Keep your eyes peeled and watch the shadows.

Superteam specializing in the paranormal? Hmm... closest thing to that would probably be The Night watch, an informal group of four mystic heroes from Britain who band together to fight supernatural evil. If you're not talking superhuman-level power, the Trismegistus Council is a worldwide association of benevolent occult scholars who study and watch for supernatural threats, and often act as a resource for magic-based heroes.

Many superteams have a mystic member or two, and some organizations have specialized branches for dealing with the paranormal, e.g. UNTIL's Project Hermes task force.

EDIT: I had to separate "Nigh****ch" into two words due to the profanity filter.

I'd bet that the IHA also would go after paranormal targets if it benefits them and they have any chance of success.

The Institute for Human Advancement's primary target is superhuman genetic mutants, and secondarily any other superhumans that support them. So yes, if one of the latter happened to be magical the IHA would at the very least feel justified in going through him or her to get to a mutant target. But what's been revealed about the IHA so far makes it seem they're not really trained or equipped to hunt magic-using opponents.

Is Tappan Arkwright III canonically still alive, assuming he exists in the PnP game and was not just created for the purposes of the CO lore?