I dont want to saving any files in my current system as it may be infected.
The .REG file is a registry export file, which is no more than a TEXT file containing your Serial Number and the registry key it's supposed to be inserted into. Being a text file, it cannot be "infected".
In my situation, will I get trouble or need extra steps to re-activate my product in my new Windows (with same hardware but I will overclock then)? Will the activation system treats my re-installed Windows as another new system and consume a activation limit? Can I just simply activate it just like what I have done last time?
The one and only reason to have a .REG file to begin with, it's JUST to save you from having to MANUALLY type the Serial Number, that's it. It has no other use. Regardless if you insert the Serial Number using a .REG file, or type the Serial Number manually, it's exactly the same.
A new Windows installation from scratch WILL consume an activation, even on the same hardware. But of course, if you DEACTIVATE before reinstalling Windows, you'll recover an activation, so the net balance will the same as if you never consumed the activation.
Also, I saw Activation Auto-reclaiming in the manual, but sorry that I cannot really understand. I would be grateful if you could further explain how can I be benefited in my situation.
Auto-reclam of older activation means that, if your LAST activation was obtained MORE than 90 days earlier, even if you forgot to Deactivate AND if you already consumed all your 6 activations, a new activation will be granted anyway, without having to contact us for a manual reactivation.
The ONLY time you might have "trouble" with the activation and will have to contact us asking for a reactivation is when ALL the following is happening at the same time:
- You have reinstalled Windows and/or changed a major hardware component
AND
- You FORGOT to Deactivate before reinstalling
AND
- You have consumed ALL you 6 activations
AND
- Your last activation was obtained LESS than 90 days earlier
If ALL of this is happening, then you'll see a message like "Too many activations" when trying to reactivate, and you'll have to contact us, asking for a manual reactivation.
In addition, I have read this post (http://www.fsdreamteam.com/forum/index.php/topic,5481.0.html) mentioning supported aircrafts. May I know if it supports Aerosoft Airbus A320? As it is still a new products, so I wonder if this posts are not updated...
The Aerosoft A320 is in that list of the thread you linked. It starts with it...
Moreover, how does GSX support freighter aircrafts like PMDG 777F? I worry that it will have passenger bus for the freighter 
. Do I need additional steps to make GSX support it?
GSX doesn't recognize a Cargo airplane as such, so it will have a passenger bus IF you are parking in the open. We are working on a Cargo Expansion product for GSX that will treat Cargo airplanes correctly, with more realistic operations and proper cargo handling.
