For the header images you could use the
Dynamic Headers plugin. You would use the code given in place of %image in ATO>Style & edit Header Area.
For different sidebar layouts you could either use the boxes in ATO>Style & configure Sidebars to exclude the sidebars on certain pages or you could use the instruction in the Gold forum to build a no sidebar page template but this does require a $20 donation to enter. The instructions make use of a modified and renamed index.php. This may give you insight on how to create your own page templates.