At the very least, the module system should be a great tool for you to learn PHP. When you do PHP tutorials, you can use that to quickly test your work through trial and error. I wouldn't recommend editing modules on the "Edit Module" page because if it errors, you won't be able to fix it on that page. Though if something like that goes wrong, you can browse the site tree for the broken module and fix it through the manual editor.
The best way to do it would be making a page for testing {admin protected}, in which you'll work on by switching tabs in your browser between the module editor to the testing page. I can do this much faster then editing+uploading+refreshing page. It's arguable whether or not it's faster than using notepad++ and refreshing via localhost server.
Anyway, I hope everything goes well, and who knows, in the future it may have a forum package you can snap onto it ;)

