You could use regular Polyester or Kitty String for 2A right?
If the yoyo has a ball bearing, sure. It can work. I think that’s what Patrick Mitchell and Joseph Harris are using these days. If you like it more responsive you can go for Fat Kitty.
Yes, you can. The threat of string breaking in the middle of a trick is almost nonexistent because you’re gonna change the string when it loses its good feeling anyway.
I know a few folks in the Philippines who use Kitty String, while Patrick Mitchell uses YYF’s own 100%poly string.