Hello, i also have a swiss 16Gb n9 and i updated it from PR1.2 swiss (ARM 232) variant firmware to PR1.3 central europe firmware (001).

So you can use other firmware yes. But be aware that, it will not flash a firmware version below the one you already have on the phone. (this means that if you already have the PR1.3 swiss variant, you cannot change anymore and have to use the same)

And i would advice to not install the chinese one or russian or something with special alphabet or software restriction (asian version is missing some software and services coz of internet freedom).

But, i checked the picture of your phone and would say that you should return it to NOKIA for repair, because it seems it has taken a serious chock.

EDIT: A link for a great N9 flashing guide: http://talk.maemo.org/showthread.php?t=82693