It’s only 1,900 to extend, but at the discretion of immigration as to whether they give you 60 or 90 days...I always got 90 days
If you leave while you have still more time on your stay, simply get re-entry permit that allows you to return and continue to stay up until the expiration of the stay
You still need a work permit...the only change was for some very temporary roles...such as business man attending conference etc...and some others of similar transient nature
To volunteer full time there has been no change...I know of people who are getting their work permit for volunteering as we speak...