kernel module parameters changes (using /sys/module)
1) Yes, /sys/module indeed has all the modules.
2) No, /sys/module/xxx/parameters only has the parameters the module wants to export, that is to say if you want to export some kernel module parameter from your module, you should use:
module_param(test, bool, 0600);
where the last parameter is non-zero, which means the permission of the file "/sys/module/xxx/parameters/test".
3) No, the value of the kernel module parameter is almost static, rarely changed by other places.
4) Your kernel module shall notify the userspace application.