Hello and welcome, panacoic!
The intent of rootcopy is for it to hold things like scripts and config files, because it's easier to add and remove them, modify them, etc than to extract and compress modules for minor modifications. That said, I don't know that there's a theoretical limit on how much you can place into it (there are realistic limits, based on your hardware, of course). You could, for example, extract a module and place it's contents in rootcopy and have the contents available in your live filesystem. However, rootcopy is not as efficient as keeping those files in a module. In a module, the files are compressed, so they occupy less space, and the modules are mounted, whereas the files in rootcopy are actually copied from the rootcopy directory into your live filesystem (using up more of your RAM). So, if you add a ton of files, your boot time will get slowed down a bit and your system will run a little slower. Also, if you're running porteus off of a FAT filesystem, it won't support file permissions (which could cause security issues) or symlinks (which could break things).
If you have modules that you want activated every time you boot up, then place them in /porteus/modules/ on your storage device, and you'll be set.
Rootcopy does work in "Always Fresh" mode -- this is how I run my system (no 'saved changes', but when I want to specifically modify something, I make the change and stick it in rootcopy). This will change a bit in the next release candidate for version 1.2 -- the 'Always Fresh' menu item will ignore magic folders, rootcopy, and all modules except the ones from the default ISO (making it more of a 'disaster recovery' mode). You'll still be able to boot without changes with rootcopy and extra modules, however, simply by removing the 'changes=' cheatcode from the typical KDE or lxde boot entry.
Good luck, and let us know if any more questions pop up
