The minimum requirements for Leopard are a G4 867. So barring forcing it to install, it's not an option, and I doubt it'd run exceptionally well anyway.
it can be installed with some hacks but might run a little slow... i'm happy with tiger 10.4.11 and is pretty zippy on my dual 500. stick with tiger is my suggestion.
No, he said he used Firewire Target mode. Pay attention!
It involves connecting your computer to one that meets the minimum requirement via Firewire cable, and installing from there.
Of course you could remove your drive, put it into an external case and use the qualifying computer to install it there, but that's a lot of unnecessary steps.
both worked for me. FYI leopard runs faster than tiger for me, the system pull is less on my imac g4. Tiger pulled 7-8% on the cpu. Leopard pulls only 2-3%