Please check the theme documentation which came along with the template. You can find the answers on your questions there. Just in short:
1. For the slider on top, you will have to use Revolution Slider.
2. You will have to add portfolio items and create a new “Portfolio” element using the Content Manager. The only problem is, you cannot link to the category archive in which the portfolio item is. In “Portfolio” item, you will have to specify which 8 element you want to include. If you don’t, the latest items will be shown.
3. You will have to create a grid with 4 columns in a row in “Content Manager” on the home page. Then, you will have to insert 8 “Blog” types from “Content Manager”, one in a column. In each blog type, you will have to specify from which category are the posts showing.
If you still haven’t, install the theme and look trough it. It is not that complicated, but if you have never seen the “Content Manager” panel and portfolio, you will not understand what am i saying.