Hello,
I've noticed if I view my website on different screens (ie. a laptop and a monitor) they appear cropped at times. The images appear cropped at the bottom but on the laptop I see the whole image? (I realise you need to scroll to see the end of the image as it won't be to the exact screen, but didn't expect it to actually crop the image depending on size of screen.
My images size are 3000px x 2000px ... is that too large? Wasn't sure if resizing would effect the quality?

Yes, 3000x2000 is a lil bit to much, but the size is not important, the ratio is!! I would ake a 16/8 ratio
But you can setup the max height in template options > layout


But the other way is, to disable the slideshow in mobile devices. Therefore add a module class suffix to your slideshow module, shown below