Dear Gust,
There are 2 help pages for MCFactory
One in the MCFactory module itself and one in the modules you create with it. (both by visiting the "Module Help" link)
The "actions" are PHP and you can call them by using {ModuleYouCreated action="ActionName"}
I haven't used "Custom logic" yet so I can't tell you much about that...
Once you "publish" a module, you still need to "install" it. (Extensions >> modules)
If you edit a module that was already published, you need to clear your cache to get the module to reappear. (no need to install again though)
You can create multiple modules and select your main module as "Parent module". This will show the extra modules in an extra tab when adding records in the main module.
To edit the templates of the extra modules, you temporary need to clear the "Parent module" selection to get it to appear and gain access to the templates. And while i try to avoid adding extra records while they are not "connected", i suspect this wouldn't cause any issues.
To find out what you can do with the templates, check out the contents of the various default templates. They will automagically include the fields you added to your modules. You find the default templates by choosing "Restore template from:" in the modules you create. Warning: This overwrites anything you already have there...
I really love this module but I wouldn't mind some more extensive documentation or some in depth examples myself
Watch out with special characters in some fields, i remember breaking the cmsms setup at one occasion (but hey, that's why we backup before messing around don't we?

)
I'm hoping some other MCFactory fans will post some of their tips/tricks/examples to this thread!!
Greetings,
Manuel