The cheapest way for a foreign car license holder to get a VIC motor license?

Hi,

I'm currently on a WH visa (417) and started to think of getting a motorcycle license.

I have a car license and haven't converted it to a VIC license as I didn't intend to drive a car while I'm here.

I've read some people choose to get a VIC car license first to make it easier for them(?). I don't really understand how everything works (What's P1 P2 and how are they different?)

I eventually hope to convert the VIC motorcycle license to a Japanese one where I'm from but I'm leaving early next year, and I also wonder how the restriction (under 3 years) works when converting it there.

Does anyone know or what I could read up to get myself more informed? Thanks a lot.