Figured a few things out for those that are reading this later:
- The reason the upgrade button was greyed out was because I had my Air Canada Aeroplan number attached to the booking. In order to upgrade with points, you have to attach your Kris Flyer number to the booking. Then, log out and back in. Voila, button is active.
- They were not able to hold the award upgrade for me because it would have created a "duplicate segment" on the booking, oh well.
- If there are Saver seats for the flight and class, then there is also an upgrade available from Econ. to Biz or Biz to First, as long as your booking class allows upgrades.