1. "on demand" let you download (not install) an application and its dependencies; you can then install the app. and its dependencies when you want to use the app.;
2. once mounted, the apps can be unmounted, but libs, symlinks and other related files (docs, lang support etc.) remains installed in the system; there are some scripts in the forum in order to unmount apps and remove related files like deps, but they can make your system unstable; at this point, the igelle approach differs from the TC approach; TC lets you install apps and deps for one session, and the system returns to pristine state when you shutdown your computer; you can build scripts in order to have everything you want mounted and installed at boot and you can use a backup file in order to restore preferences; as well, you can decide to boot at the pristine state and mount what you want while using TC;
3. hardware detection: you can remaster TC to fit your hardware specs with drivers and firmwares you would need, or you can use TC with scripts built to mount everything your hardware needs at boot; so yes, there are multiple ways to automate hardware detection, but it depends on your knowledge of your hardware; now, as stated in the introduction to TC, TC is not suitable for every hardware; here, too, igelle differs because they want to have a cross-hardware os;
4. there is something similar with TC regarding the use of deps files which are txt files listing deps for an application; once you want to load an application, TC reads the related dep file and mount the needed dependencies;
In my view, there a lots of similarities between igelle and TC, the point where igelle would go further is its capacity to be used in several architectures; i would hope for a similar developpment for TC which would be (given its size and small footprint) the best bet for arm processor and other mobile devices.