I doubt that Sandisk is going to be the only company that makes the memory, there are always third party versions, but it is most likely the safest bet to stick with whatever is the offical memory card. As for size, look at the sizes of the cards now. I doubt you will need one right away if you are only using the system for gaming and not transporting information to or from a pc or another Wii.
Wii points are what you use to purchase content on the virtual console, such as NES games and what not.
If you are talking about how much memory or wii points an item costs, then I would say yes it would be on the game itself. If you are talking about the GameCube controller, it probably will be up to developer, safe bet if you think it will use the GameCube controller, research it on the net.