When you want to override CSS values you can do two things: adding new CSS declarations after the one you want to override or using "!important"..
So for your problem you can try:
a.reset:hover {
background-color: #FFFFFF;
text-decoration: none;
color: #000000;
}
.. and then add the links you want to override this new class:
<a href="#" class="reset">Link with reset</a>
But this CSS class must be declared after you normal "a" tag declarations or this won't work.
Another way is to use !important but I recommend not to abuse this one. But for overriding it's the fastest and safest way to be sure it will work:
a.reset:hover {
background-color: #FFFFFF !important;
text-decoration: none !important;
color: #000000 !important;
}
.. and this one you can add anywhere in your CSS file and any link with the "reset" class will get those styles: white background, no text decoration and black text.
Oh and for the background you cand try: background: none; and will clear all background styles.. background-color, background-image, etc
As a side note.. id's are used to reference a single element and it must be unique.. and classes are used to reference multiple elements. Multiple uses of the same id as you would use a css class.. you can brake javascript and it won't validate your HTML.