the thing is with that arch=i386 some of the trackpad options are 32 bit only and some models are intel which do not have 64 bit video drivers, in order to maintain compatibility then we run it at default 32 bit, feel free to select a 64 bit trackpad option and remove i386 to as Nvidia, Core2duo D830 supports 64 bit.
Kernel
mach_kernel
UseKernelCache
Yes
0
is used to speed up your boot times.... feel free to remove em if you like long lasting boots... cheers