Use FSI_Batch (a front-end for ChangeFSI) or similar to create 95% jpeg images which fit 800x800 and 240x240 (Lock aspect). As FSI_Batch barfs if the filenames are too long, you may find it easier to make temporary copies of the originals in RamDisc. This can be quicker too. With enough large digicam images, you can go and have a sleep or a meal while FSI_Batch and ChangeFSI do their thing. Obviously, making the 240x240 images from the 800x800 images is much quicker than from bigger originals. Take care to transfer the new images from FSI_Batch output to the correct directory; there is no need to change the filenames. In fact, it's best if you don't as the images and captions correspond only if they are in the same alpha order. Preserving filenames ensures this.
To create the Caption files, shift/drag your images from 'originals' to a new StrongED Obey file to 'type in' their full paths for you. Use S&R to change ".originals." to ".captions." and change "/jpg" (or whatever) to "/txt ".
Use block edit to precede each line with "Create " (Not the " but it needs that space). Save the Obey file to RamDisc and run it. Select all the newly created files in .captions. and use the menu to change their filetype to 'text'. You can then drag all of them to your favourite editor to write captions; match the filenames to the images with the same leafname sans /ext
(Quicker to do than write that explanation!)
If you install WebJames, make sure you install the version with PHP. This can be on your local machine or another on your network.
(I can't find WebJames' new home. Alex Waugh's site seems to redirect to Google. Here is a copy of Webjames version 0.48 with PHP it's an ideal use for a Pi).
If you install the contents of carousel/zip to a directory called 'album' in the web root served by your local machine, the address you visit is http://localhost/album/