Can I setup a separate payment account for each currency?

The Recurly-Xero integration does not currently support creation of separate payment accounts for each currency. You can only select one. You would need to have more than one Recurly site, each setup for a different currency so that you can connect them to separate payment accounts in Xero (if you had to have separate payment accounts).

Xero will record the currency in the Invoice record and Credit Memo (for credit invoices) record.