Apple, reading your post is like reading something I'd write. Our thought processes sound very similar in that I, too, find that my panic attacks are different every time: in duration, intensity, sensation(s), the reason behind them, etc.
I think it's very difficult to stop a panic attack in its tracks, once it starts happening. I'm not sure hot possible it is to just surrender to the feelings and sensations instead of analysing them. Saying that, the reason why they happen sometimes is because of over-analysing.

To answer your questions, on rare occasions, I'm able to prevent having an attack because, as soon as the anxiety kicks in, I start thinking about the reasons behind it. I ask myself the question 'why am I feeling this way; what may have caused me to feel this right now; which events and thoughts preceded this state?' Usually, it's work-related stress, or sometimes it's anger, an unresolved situation, a feeling I channel into panic.

More often than not, however, it's a reflective process. The thoughts and actions are different every time, though I'd say it's predominately a fear of fear that causes my attacks.

Sorry if this reply is so long, I wanted to be as helpful as I could be.