I haven't had time to install Mountain Lion yet, but I already know the reason for #2 and #4. Defective NVidia chip. .
Good to see that you're still around. You are absolutely right about the defective chipset issue on XPS M1330. It is a well know issue with the 8400m GS GPU. This was publicised a few months after it release. Hence it is an issue with M133's mostly. That is why you'll hundreds of M1330s 'For Repair' on Fleebay.
That problem has been corrected on the 'GT' versions and therefore not applicable to M1530 based on 8600m GT.