I will be staying at the Caribbean Beach Resort on Sept 16 for 7 days....I am so excited.

This is our very first trip to WDW. I have a 3yr and 1yr old. I have requested for the Jamaica Bldg 45 or the Trinidad North. Is it a long walk across the lake to the Old Port Royal? Am I better off at the Trinidad North or even the Martinique? I was thinking the playground looks close by to the Jamaica Bldg 45 that's why I picked that one. I have paid for a water view room. Anyone's thoughts are greatly appreciated.
Also, do they sell the princess autograph books at the gift shop?
Thanks!