1) Of course - xONEn is not a ticket type that requires people to travel together!

2) Assuming that the ticket is on BA ticket stock then I would talk first to the BA RTW desk to get it set up for collection at the BA desk in SEA. However, the downside to this is that you will probably get hit for GBP25 (or equivalent - not sure if that is per ticket or per request) plus any increases in fuel surcharges plus the USD125 change fee (per ticket) by BA, whereas AA would only charge you the USD125 change fee.