Hi, Sue!
I'm just thrilled that you're finding lots of helpful information here on the Disney Parks Moms Panel! We all really enjoy helping Guests with their vacation planning questions!
You are absolutely right that the buses run from the Disney Resorts to the Theme Parks as well as to Downtown Disney. When you want to travel from one Resort to another, you typically always have to go to a Park first and then switch buses to the Resort you want to go to.
I really love to use the Transportation Wizard located at OurLaughingPlace.com. If you look at the upper right-hand corner of the site's homepage, you'll see the blue link right there. Once you click there, you'll see a drop-down menu where you'll be able to select just about any location on Walt Disney World property to travel to and from and it will give you all the available routes and estimated times of travel. It's the BEST EVER!
To travel from Disney's Caribbean Resort to
Disney's BoardWalk, your best bet would be to take a bus to Downtown Disney and then hop on a bus to the BoardWalk like you said. Another option would be to take the bus over to Disney's Hollywood Studios and simply walk over to the BoardWalk.
I hope this helps! Please come back and visit us again if we can help with any other questions you have!
Wishing you Pixie Dusted vacation planning!
~Jackie