Good question. I have never heard of this being done. The only way I know to change your reservation prior to your trip is through the Central Reservations Office.
Once you are at the resort, you can talk to the front desk to see what is available for rooms at the time you are checking in. They might be able to give you an idea of the possible views from the room you are assigned to, or others that are not occupied. They may even be able to give you the price to upgrade to another room category if that is what you want.
Yes there are and yes, they are Lagoon or Garden view. These would be the rooms bordering the wedding gazebo and some at the end of the resort near the YC quiet pool.
If I'm not mistaken (and I could be), some of the rooms down at that end of the resort were the ones where they were trying to book guests with dogs.