Thank you. Those are ideal questions.
On GST room, the benefit to the consumer would depend on the province you are in and how much of the available room a province chooses to take up. If you're in Ontario, with a relatively rich tax base, you might find that the province will choose to take up less than other provinces with weaker tax bases.
The more important point, though, is that I would encourage provinces to reform their retail sales taxes precisely because of their pro-growth, pro-investment, pro-employment aspects. A retail sales tax like the ones that exist in Ontario, Manitoba, Saskatchewan, B.C., and P.E.I. all involve a certain amount of cascading of business costs. Improving tax treatment by way of a value-added tax would be an important stimulus to economic growth and ultimately to employment wages.