I don't know about the console font format, for a normal truetype font, I could use gnome-font-viewer to preview it, but what about console font? If I don't switch back to another tty, and use setfont command, is there a way to view it in X?
I don't think there's any widely-used tool. Try psfedit. There's also NAFE which lets you convert between console fonts and an ASCII pixel representation, or Cse to edit a font from the console. I haven't used any of these, so I'm not particularly recommending them, just mentioning their existence.