can the ADD to CART button be resized and image changed be done without any coding?
well...you will have to work around with some CSS. Try using Firebug, that can help you a lot.
In the CSS folder file vmsite-ltr.css, on line 50
span.addtocart-button input.addtocart-button,span.addtocart-button input.notify-button{width:152px;background:#e8e8e8 url(../images/vmgeneral/backgrounds.png) top repeat-x;background-position:0 -160px;color:#fff;border:solid #00a000 1px;border-radius:4px;-webkit-border-radius:4px;-moz-border-radius:4px;font-size:14px;cursor:pointer;height:34px;text-align:center;letter-spacing:1px;padding:4px 5px;}
You can put in a new image to change the colour or edit backgrounds.png, change size and border colour etc.
Hope this helps.