The slider gallery of pictures on my website move a little too quickly for my liking. Also, they're a bit too large. So, what I'm hoping for: slow down the automatically advancing pix by 1 second, and reduce the amount of 'real estate' upon which the gallery sits by about 1/3 - 1/2. THANKS.
Which slider plugin are you using? Did you check the plugins settings? If size and speed settings are not offered -- there are other slider plugins to choose from.
The only restriction would be if the slider is meant for a specific space within your theme -- then the size needs to fit that space. Changing a theme's established real estate would require custom modifications. If you slider is on a page/post or in a widget, that is not a concern and you can config to what you want within the plugin settings.