I have noticed that if I create startup scripts in this folder they are not automatically loaded upon startup.
is it possible to automatically load any script in this folder.
is it possible to automatically check this as opposed to run before unmounting in the web interface
Tomato isn't a desktop system, so it doesn't have the typical /etc/init.d startup stuff. It wouldn't make sense to, nor would it even help. In a standard system, the boot disk which has /etc is mounted as part of the early startup. Actually this happens in Tomato, too, but the boot disk is in ROM and the filesystem isn't writeable, so there's no way for users to customise what happens at startup. Tomato's startup processing is hardcoded.
Anyway, the usb disk isn't mounted at startup - that doesn't happen until much later. The disk that /opt is on will get mounted when the USB subsystem detects it. And this won't happen until long after startup has finished up.
I wrote a detailed explanation a while ago of what goes on during startup, and how autorun/stop work — maybe you can find it.
That's why I invented the autorun & autostop facility. You need to do what you want to do in autorun/autostop scripts. Of course, you can still have your "real" script in init.d, just have a skeleton autorun file that invokes it.
Autorun/stop scripts are far superior to the run before/after unmount/mount rules in the web interface. If you are clever enough, you can even have autostop scripts that will kill a process, and which will work even if the USB disk gets unmounted by being unplugged. (Obviously, a script that is on the disk can't be executed if the disk has been yanked out.)