I would highly suggest you put in a ticket to support and ask them this question of compatibility with the shopping cart as I'm guessing most of this will be done using the Designer (just guessing though) and although the cart stuff will need to be compatible, they are usually pretty good about making sure their previous created products are compatible with the new ones. Using Form Builder as an example, I don't think it ever had a build that you couldn't open your last created forms with the new versions and have them work.
Just saying I'd ask them and see so you don't sit and wait if it won't be of course, but this way you know if you should wait on getting the package deal or not as well.
As for your question on pages, I believe you can add up to 5 extra pages to the cart which will show up as a drop down under either your Home button or the Shop Home button (whichever you set it up to do). So although that answer is yes, it will not show on the menu bar, just as a dropdown. I believe there's some posts elsewhere on the forums that may address this and someone showed how to make it show on the bar, but I don't recall where that is sorry.
