The FCOMs and other documentation come with the plane. Click the Start icon, then click All Programs and the documentation is in the PMDG folder.
Cheers,
Ian.
I think I read somewhere that RAM amount matters hugely to FSX and sometimes too much can basically slow things down. You have 16Gb installed...maybe try removing some RAM (if you have mire than one stick installed) so that you only have ~4Gb. Cheers,Ian.