Can't help you with all you are asking here but:
* If you want as quiet as possible, you want to get silenced versions of which ever you choose ( or get O-rings and apply them yourself ). The red are a bit louder if I'm not mistaken, but I would guess they are approximately the same once they are both silenced. The browns, unsilenced, might not be super loud depending on your tastes, but if you are trying not to wake someone or something you will prob want to silence whatever you get in the mechanical space.
* If you are using it mostly for games, and you like them more, go with the Reds! I'm sure they are still great to type on. They are probably still better to type on than your Logictech
I would personally go with the browns, but Im a coder as well. The browns still play games great as well.. I think for games, you really will only have a preference if you are super tempermental/particular about how you depress the keys.
* As far as the test keys, I don't know of any test keys sets you can get that are bigger than the typical 4/5 key ones you see. Maybe someone else knows of one. Your best bet is to find the biggest box PC parts store you can find around there ( Went to a PC World in Birmingham once that wasn't too shab, but that was years ago ) and see if maybe you can find some display units of the Corsair K70.. There are a few best buys out here in the states that might have both the brown and red models out on display, but YMMV obviously.
Best of luck to you! Let us know if you get anything and what you think of it!