Buildings are destructible, yes. But "destructible" does not mean replacing the building model with another. Dynamic destruction with physics...

Confirmed. Place a tank and give him waypoints all over the city with "FULL" speed. He crashes at nearly all curves and corners.

Same here, Win 8.1 x64, Saitek X52, Arma III 1.34.128075

• Start game without mods.
• Open settings menu and go to controller page.
• X52 is detected as is should.
• Open editor, start game.
• Open settings menu again and go to controller page.
• X52 is missing now.

Little addition?
In combat mode, AI driver should not care that much about "neutral" units in his way, because of the following issue, happend to me yesterday.

8 man in APC with AI driver. Threat (RPG) from behind. AI driver refused "fast forward" command, because there was a civilian >>NEAR<< the APC. He actually could drive forward without hitting the civilian but I think the way calculation failed...
-> 8 man + APC down (civilian too).

Same issue:
i7 2700k, GTX 680, Win7 x64
Running arma with -cpuCount=8

Just walking and shooting around on empty stratis map.
CPU states:

• 1 core: about 80%
• 3 cores: about 40%
• 4 cores: 0%

GPU usage: about 80%

I think this problem is not easy to fix. Seems to be bad engine design or maybe the engine is a bit outdated. Or maybe only the resource management is ****. I saw benchmarks where a GTX 680 has nearly the same performance as a GTX 980. That looks like there is some kind of capability that is not used. So maybe they could use this capability for other computation (I mean something like CUDA).
I am not an expert, just thinking and adding some ideas...

Also they should stop adding more content because there are so many needed improvements for the game, from crash/performance issues to realism issues.
There is no other game like Arma, so keep supporting and developing...