The combustion chamber is some alloy of iconel. I can't remember if the needles are on a P-80.

The details of the chamber design control gas flow so who knows how it will run on methane. At least you don't have to worry as much about atomizing the fuel.

If it is hard to ignite you can use a spark plug or a piezo ignitor.

The fuel system is designed to send some fuel/oil mix into the bearing tunnel. You can inject some sort of lube into the same inlet port, could use compressor pressure to force the lube in, many of the first hobby turbines used this technique.