I believe in the province of Ontario it is a province wide law that forbids anyone under the age of majority from purchasing any form of airgun or airsoft device.
On the topic of Age verification only the actual user of the account in question can be verified. Parents cannot be age verified on behalf of their children.
As for information in regards to rails, I believe the standard used rail is simply a 20mm rail. For more information on the topic you can refer to this wiki link
http://en.wikipedia.org/wiki/Picatinny_rail