Hi,
You can use CSS to target different screen sizes for blocks of pages or specific pages using the classes found in the html body tag.
Open up a page in your website and view source and look for some class in the body tag that is unique to that page. lets say its class called page-id-225
you would add another css block as above but make it look like
#top.page-id-225 .medium_sized_slider, #top.page-id-225 .medium_sized_slider .featured {
width: 576px;
height: 260px;
}
I am not sure I understand you question about the slider automatically sliding. That should be happening anyways, because as my grandpa always said, a slider that don't slide ain't worth a half penny. ;)
Please explain.
Thanks,
Nick