Grub 2 typically gets overridden when you install Windows or another Operating System. To make Ubuntu control the boot process, you need Reinstall (Repair/Restore) Grub using a Ubuntu Live CD.
Linux Kernel 3.10 is the most recent LTS kernel release, with 18 releases to date. With a plethora of fixes for literally thousands of bugs, the latest updates stress stable network connectivity.
Linux Kernel 3.11 is mostly a driver-driven release, with fixes for bugs and updates for Radeon, Intel i915, Wireless and USB devices, as well as the standard list of bugs and security fixes that simply can't all be listed here.