Yes that is where your Nandroid Backup you made in your custom recovery comes into play... Restore your backup. Look around you might get lucky and find someone way back some time ago when the Nexus was first released that posted the bone stock kernel. No guarantees but its worth a look.
Correct. Flashing the kernel will not clear anything out.
2.) Flashing a kernel doesn't wipe anything out right?
CM has always had okay battery life at best. CM focuses on the ROM ' OS ' and not so much the kernel.
3.) Which is better? The Revolution HD ROM or CyanogenMod 10 ? The latter reported to have battery issues earlier .. from what I've read.
No. You can use any kernel you like on any ROM. But as you have read already, kernels react differently depending on which ROM they are installed. Just a lot of trial and error. Again.. Make your backups
4.) Are there any ROMs not compatible with the Lean kernel?
ROM then boot up, shut down and go back into recovery and flash the kernel.
5.) Which do i flash - The kernel first or the ROM first?
Glad I can help. Your thanks or likes is good enough for me :)
Thank you for your support. Any place I can write a + report on you? <3 :D :D :D