As far as I can see the only things that you might need to alter are the speed of the slideshow (how long each slide remains onscreen), how long the pictures take to fade in and out, and how many images there are.
You will have to number all your photos 1.jpg, 2.jpg etc. then to add more pics to the slide show you just add their numbers to the array
Pic = '1.jpg' Pic = '2.jpg' Pic = '3.jpg' Pic = '4.jpg' Pic = '5.jpg'
so the next photo you add will be called 6.jpg and you will add a space then Pic = '6.jpg' at the end of that line.
To vary the length of time each slide remains on screen change the "5000" (milliseconds) in this variable
var slideShowSpeed = 5000;
but try both this and the next variable at the speed that is already set before you start changing things.
The "3" (seconds) at the end of this is what you change to alter the speed of the fade in and out.
var crossFadeDuration = 3;