I have two comments.
With respect to your first question, I think there are times when it seems as though it would be helpful to have different age gates for different types of scenarios, but given the explosion of the array of different types of services and offerings and context, it's incredibly difficult to operationalize those. PIPEDA has been excellent because it's been agnostic and not prescriptive.
That being said, can a 12- or 13-year-old give consent? It could be in a decision-making capacity, but certainly those under 12, the same way they wouldn't otherwise have capacity if incapacitated by other means, wouldn't be able to provide a valid consent.