Not easily. The original battery is manufactured by Samsung, and you can find photos of it on Google. As for the OS.... well, check menu-> Settings -> About Phone. You can find the build number and the kernel version there. Trouble is that a custom rom can have the same kernel version and build number as a stock rom (these values are up to the rom chef), so there's no guarantee they have not been tempered with. Also, stock kernels have many different names to begin with, and some of the names are quite funny/ridiculous.