nVidia does not provide low power, low profile graphics solutions. If we are talking Intel, it's likely to have an underpowered Intel graphics chip. The PowerVR SGX within the OMAP3430 is one of (if not) the best when it comes to mobile graphics.

I'm highly against any x86 processor due to the amount of heat generated and power consumption by an x86 core. Intel's ULV line (including the Menlow) shows that an x86 CAN get relatively low compared to other x86 cores, but only by butchering said core's performance and speed.

Accelerometers are tiny and very possible. Personally, I'd go for full sized SD cards again rather than Mini/Micros because they're cheaper and higher capacity. GPS could use an improvement
Old libraries should work as long as there were not filesystem structure changes or did not depend on a certain kernel. However, they may conflict with other libraries and newer apps that require a newer library.