1, You can use QuickStart or Theme for your website. QuickStart has sample data(product, category, cms page, static block, blog, ..) like our demo. However if you using Theme you can import cms page, static block. The code in Theme and QuickStart is the same, only difference about data.
And to install our QuickStart is so easy. Why you dont can?
Note: video has record on Macbook, so it has some common about chomod

2, You can install your module and call it on your homepage via Admin >> CMS >> Pages >> Your homepage >> Tab: Design >> Field: Update Layout XML. If you have trouble please tell us know

3, Please check config in Admin >> SNS Theme >> SNS Ajaxcart and compare with our document(13. SNS Ajax Cart)