I just worked out #3. I found the option in the module payment section of GCO.

I have another additional question though.

4 - With GCO working now, if a customer clicks on the shopping cart, GCO is not an option for them as a method of payment. Without any other method of payment but GCO, they run into a dead end. How can I make it that the GCO option appears as the only option in all areas of the shopping cart?

Thanks!