The brushes normaly color in greyish. After u brush just use the color balance (ctrl +b ) to colorize
for the fill bucket nope. just click on the square color thing, to the right. click on it and enter the color u want in hex codes. ex: FF0000- red 0000FF-blue
If you colorize after brushing you get an all 1 color sig. Unless you do more than 1 layer of the colorizing. Its very easy though. Just click the brush tool. Then click the color that you want from the box on the right ^_^