Hi,

1-) After modifying the colors to what you want, add the codes below to end of the dark.css;

To change menu link color use custom css;

#nav ul li a { 
   color: #bbb; 
}

and to change hover color use code;

#nav li a:hover, #nav li.active > a, #nav li a.selected:hover, #nav li a.current, #nav li a.selected, #nav li a.current-sub { 
   color:#fff; 
   text-shadow:none; 
}

2-) Open, css/bootstrap.css in a tex editor, and find line : 331, change the css codes belong to success button, the code starts with;

.btn-success { background-color: #5bb75b; 

There are some css3 gradient definitions for backgrounds for multiple browser including two color for gradient, one is start color and the other is end color. You can change them to any color you want.

For more info about css gradients chechk this link;
http://webdesignerwall.com/tutorials/cross-browser-css-gradient