1) You need to look in the fiche Brake section, Brake Pipe, Front. See part 5. Is that it?
2) To find out what the differing tube lengths mean, you'll need to carefully disassemble each fork leg, aligning the parts as you go, then compare. Speculating now isn't productive.
3) I'd take a small screwdriver, stick it under the outboard edge of the sleeve, then spray full blast between the sleeve and the bar with penetrant using the small tube that usually comes with a can of the stuff. I'd do this around the perimeter in a few places. I've never disassembled or assembled heated grips so take this suggestion with a grain of pink Himalayan salt