Can i flash the image of OS to 16 gb Emmc and run my system over Emmc?
The devkit uses Micro SD card. But the production Nano module will have eMMC, and that will be flashed by the NVIDIA SDK Manager or by using the L4T tools directly.
How can I get NVIDIA SDK Manager or L4T tools and how to use it?
SDK Manager is available at the Jetson download center (https://developer.nvidia.com/embedded/dlc/nv-sdk-manager).
The host-side L4T tools are installed by SDK manager. By default, for Nano, they will be installed at ~/nvidia/nvidia_sdk/JetPack_4.2_Linux_P3448/Linux_for_Tegra.