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The mirros from your other machine should work, they're usually the same size. If they are no good search for K9 CO2 mirrors on ebay.

The cooling fan is needed for small parts - if they're not cooled, heat builds up in the part and it melts. The fan is normally off for the first layer and is then turned on for subsequent layers -...

Yes, unzip them with this; http://www.7-zip.org/

I assume you looked here ? http://www.hflaser.com/download.html