Couple of other minor things, then:
In the fastwrites script, if fast writes aren't supported by the card, they'll never be enabled by the driver. So I'm not sure that entire section is needed -- unless there's a good reason you put it there? Same thing is happening with the SBA script.
In the same script, you might want to check /proc/driver/nvidia/agp/host-bridge as well, since not all AGP bridges support fast writes. Same with the SBA script -- check host-bridge.
You might want to check that the /proc/driver/nvidia directory even exists. If not, then say something about "the nvidia kernel module needs to be loaded before you can run this test" or something.
Is the multiple-IRQs script depending on the nVidia IRQ being XT-PIC? Because some systems have IO-APIC enabled (which generally gives more IRQs, though not always), and that field might be IO-APIC-edge or IO-APIC-level instead of XT-PIC on those systems. The exit condition in that script also seems a little weird...