Hi destroedlolo.
1. Correct. If you use the patched kernel source, no need to apply any other patches.
2. You can follow that procedure but, by TCL convention, /lib/modules/<VERSION> is for kernel modules that ship with the base system. If this extension is for your own use, no problem. If you are going to submit the extension, it is preferable to use the /usr/local/lib/modules/<VERSION> directory instead.
3. By default, the kernel modules will not be loaded automatically when your extension loads. After loading your extension, you can load the kernel modules manually with sudo modprobe <module_name> or, if you really want the modules to be loaded automatically when the extension loads, include a startup script in your extension. Startup scripts are run as root and go in /usr/local/tce.installed/<extension_name> . Take a look in your running system's /usr/local/tce.installed directory for examples of startup scripts. Yours would probably need only a modprobe command.
Hope that helps.