Re: Fingers spread or together?
I don't know how it is in other styles, but in Yoshinkan we're told to tense the fingers while spreading it out, perfectly flat. You should be able to feel some kind of energy leaving the fingers as it travels outwards. They should be perfectly tense so that the forearm's muscles and tendons are in tension, giving the arm structure for the strikes.
I think I read somewhere that O-sensei wrote about this too, and I think he wrote that the fingers should be spread wide apart and filled with ki. Maybe somebody has information on this?