How do I store granola?

Once the granola has cooled completely and you break it up into pieces, transfer it all to an airtight container. Store in the pantry for about a month, or freeze for up to 3 months.

Can I make granola with just maple syrup, and not the brown sugar?

I wouldn't recommend it. The brown sugar in this recipe helps the oats to crisp up nicely; using only maple syrup won't have quite the same effect.

Do I have to remove the water from the pumpkin first?

I strongly recommend doing so because it takes the least amount of time to get the level of crispiness you want for granola. Otherwise, you'll have to let your syrup cook off the water for 5-10 extra minutes, or bake the granola for a lot longer.