AppleScript in OS X 10.10 to Resize Safari window and take Screen Shot of that window and repeat with multiple sizes

I would like to build an AppleScript Application that when run will do the following:

1. Open up Safari and navigate to a specific URL from a list in CSV format


2. Resize the Safari window to one of a number of sizes


3. Take a screenshot of the Safari window with the filename being the url along with the screen size