Can I have the regular iPod firmware start by default instead of Rockbox?
The iPodLinux project has developed a bootloader which is driven by a configuration file and presents the different firmware (Apple firmware, Rockbox and iPodLinux) in a menu that you can choose from along with other features. Details can be found here, but keep in mind that this is not supported by Rockbox so make sure to forward your questions to them. This may not be necessary to achieve your goal though as once you boot into the Apple firmware it will remain there until you do a hard reset. Holding Play/Pause in Apple’s firmware puts the unit to sleep, it does not shut it down. So, if you mainly use the Apple firmware then just don’t do a hard reset and you’ll continue to be in that mode.