There are some additional links, mostly to useful forum posts explaining Lua concepts and such, at the "resources" link in my signature.
2. Rather than Googling for how to make a button, it's probably faster to look at the code of an addon you already have that makes a button, or even
the default UI code.
Same for events and functions -- try searching for keywords on the "
all events" and "
all API functions" lists on Wowpwedia first, and look in the related default UI code if you can't find it there. I only use Google for answering more conceptual questions, or for looking for information about specific API bugs.
3. I would not recommend using any libraries until you have a good grasp on the basics, and can make an informed decision about whether using a library will actually make your work easier, and whether the overhead is worth the gain. For example, it would be insane to use AceGUI just to create one button.