I didn't answer myself, because I don't want to re-subscribe to a group of the Thieves of Mountain View.
But also because I don't know the answers.
I do know:
Devanagari has to be installed separately on a Mac. The OP no doubt took care of that, but that information may help Igor.
PO. I'm sure I found a solution for PO that doesn't need the intervention of Our Beloved Leader (no not that one, I mean Igor). And I saved it. Can't find it. I always claim I can find anything on my Mac, but I get some 5,000 hits for "PO", and I can't think of other keywords...
Can somebody please answer a question on the old forum?