If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
You can use the R65C22P2/3/4, the R65C22 is fully compatible with NMOS 6522 devices, The /IRQ output pin is an open-drain configuration, so no problem.