There are ways to do everything you have described in this thread, but you need to understand; This is not programming in a traditional sense. Though if you understand how to use C2, your programming skills will come in very handy.
On to the questions: Setting a value depending on which button is pressed is pretty simple. Many ways to do it, but I would recommend using an instance variable:ButtonsSimple.capx (r134)
As for your other questions, I'm unsure what you mean by "trigger", a button, an action, an event, a condition? All these could be described as triggers, but I haven't used that term, so I'm unsure what you mean by it. And in the last post there's too much back and forth in your explanation, I have no idea what you're looking for.
By the way, have you read the Beginner's Guide? Even if you don't feel like a beginner because of your programming experience, it's important to understand how C2 operates. You can do almost anything in C2, but the approach is often different compared to programming from scratch.