I suggest doing online checkin first just because you can do it much earlier, and then that info is already available to anyone checking your details if a fax is received later. And I suggest 3-5 days for sending faxes as that's what the Room Assignment Manager at POR specifically suggested would be the ideal time frame for most bookings (much longer than that and there's a danger your fax will get put in a tray until they start working that time period, which could result in something being missed). Oh, and address your fax to the department, not to any individual (even the manager) as if that one person is off duty or on holiday your message could get overlooked for a while.
Andre