Question about price and pricing for the RTW:

1. Since I intent to use YYZ to start to take advantage of cheaper fare from Canada, do the agent/RTW desk must be in Canada? (e.g. AA's RTW vs BA(Canada)'s RTW Desk)

2. Normally travel agents can provide much cheaper US-Asia flights than airline themselves (e.g. My DTW-HKG ticket last spring is $8xx from agent verus $11xx which was listed fare and printed on ticket).
Can I get the OWE Ticket from agent that will be cheaper than to get it from airline's RTW desk? Again, will this agent must be in Canada or?

THANKS!!