1.) Open up style.css and find this code (around line 219):
padding: 0 0 15px 50px;
The padding left is the last of the values for padding so to increase the spacing adjust 50px - for example:
padding: 0 0 15px 60px;
2.) The colours are set in the individual colours' own CSS stylesheet. Open up /css/style1.css and around line 232 you'll find this code:
border-bottom: 1px solid #DDDDDD;
border-top: 1px solid #DDDDDD;
Simply change the colour (#DDDDDD) to the HEX value of the colour you'd like to use.
3.) The border is the same width as the sidebar area. To adjust the width, go back to the code for #1 above and reduce the value of:
Please note, all these modifications are based on the original theme files so if you've made other adjustments things may need altering. If this is the case, please post the site URL.