Some worries about trading exchanges?

Hi all;

I’ve been mining Zcash for some months ago, now I’d like to make some crypto-trading.
During my research, I notice one weird ‘currency token’ which can be call ‘USD’ tether or USDT ( in many exchanges.
I wonder:

  • Who managing this kind of tether tokens?
  • Does it have open-sourced?
  • Can they be ‘printed’ massively for (margin) trading (which made btc high dump) recently? I found this address generating so much tokens by days:
  • If it’s considered to be exchanged 1:1 to USD (according to coinmarketcap), will it can be in dangerous of being seized by FBI or government…?

Thanks for your reading and sharing…
Have a nice day.