cascading style sheet is known as CSS and basicly used for define styles of your documents, including the design, layout and variations in display for different devices and screen sizes.
I belive Infographic submission is the most effective and most recent technique used for purpose of SEO through social media . Reason of popularity of infographics is that they are more interesting from long articles and blogs .
301 redirect is Search Engine Friendly method for webpage redirection . It is a permanent redirection and will passes 90-99% of link juice (ranking power) to the redirected page.
I will suggest you to contact professional web designer to design your website, they will help you to prepare content and layout. They can design it according to your requirements and could make it highly responsive which won't be able to do by yourself.
The benifit of site map are
1. If you have site map for your website and made some changes on it then serch engines will indexed those changes fastly.
2.User and SE can nevigate esily on your site