Don't forget you can always upgrade your passes when you get to Disney. Just be sure to use them to get into the parks at least once before upgrading. This way, you will get credit for the current Disney price for the days you already have, and they will only charge you the difference to upgrade. You can also add hopper and waterparks when you get there.
I would leave the waterpark option until I know what the weather will be like first. You can always add it, you can't take it off. If the weather is cool, skip the WP. Or just pay for one day OOP, it's cheaper than adding the WP option.