You are using a full width slider. To prevent it from stretching images, simply upload large sized images. The slider dynamically changes based on the screen size of visitors, so while the images you provide don't stretch for iphone or ipad perhaps, they will stretch on other display devices.
Please use free online image optimizers ( http://www.smushit.com/ysmush.it/ ) to keep your images lean and fast.
You use an image only 800x 243 in size. Resize your browser window to make it the size of a mobile phone or tablet, and you will see that the website will readjust to perfectly fit the screen including making those same images in the slider smaller. I would consider using images that are width 1600 (twice the size of yours) so that the slider images would shrink (which doesn't cause blurriness) instead of expand as they are doing now (which does cause blurriness).
2) You mention 3 photos on the home page 'Precept/Transform/Autism photos'. Are you referring to the slider? Because I only see events, bootcamp, and contact us. I am not seeing the images you are describing. There is a great tool at http://www,imgur.com that lets you take and upload a screencast of any website, as well as provide drawing tools to label various sections. Would you please clarify the section you are describing.