I applied my oa 2 yrs ago from us, but I think it should be the same for Canada. U need the following as I remember n additional forms listed from the embassy.
1. Oa application form.
2. Medical check form as from embassy web site.
3. No criminal record form FBI from us, not sure which agency about Canada.
4. 800k deposit at yr bank in Canada for at least 2 months. Also need bank letter for proof of these funds.
5. Insurance - I apply via axa Thailand, they have package just for oa application.
Most of the above has a time limits of 2 months when submitted for application.
After u get ur visa and arrived here, u can renew yr insurance, get a re-entry permit @ the airport leave Thailand just before yr current insurance expire and come back (before ur initial visa expire) , u will get stamp for additional 1 yr stay.
Also dont say too much to bank people, when i open account i kbank telling them i am on non oa Retirement visa. They said yr stamp doesn't say retirement, only non oa. They asked me to go back immigration to get the Retirement wording. OMG!