Actualisation de site web

My website is a little bit old and I foresee to change it. It's web address is [URL visible pour les membres Pro] I see two phases:

A) quick fixes
- my website is not adopted to mobile platforms and a majority of my clients check it on their mobile (see also proposals in description document from woorank).
- furthermore the template is pretty old and it might be useful to update it.
- low number of pages (5) discovered (see description document from woorank)
- Urls not found, no 301 redirect (see description document from woorank)
- website is SSL secured (HTTPS), but the Common Name is set to *.hoststar.ch.
- website's URLs do not redirect to HTTPS pages.
- website is configured with HSTS.
- The SSL certificate expires a month ago.

B) More profound changes in termes of structure / marketing / SEO searching / design etc.)