Zero disk space used by kernel. The kernel goes into flash memory. Disk space IS however used by the root filesystem for the basic UNIX environment, it's not a large amount however, certainly a lot less than the amount you're talking about.

What you're missing could have to do with the fact that 36GB is a raw amount of bytes, and a certain amount of space is used in the ext2 filesystem itself. A long time ago there was a thread about this and I think 33GB was the right amount of real usable space for 36GB drives. I can't seem to find the thread now, though.