1 - You are checking the version 3 to version 4 section there, so you dont have that, as you arent on version 3.
2 - You should obtain an updated version of your language pack from the author, or update any changed translations yourself if you have manually translated.
3 - If this is needed, the upgrader will walk you through that process
4 - You are not upgrading from content to pages. As mentioned above, you are looking at version 3 to version 4. Thats not the process you are running. You are already on version 4 (you're on 4.3)
5 - This is not something that is available any longer. If you wish to use pages at root, you would move your site to root and set pages as the default application. You can see how to do this here https://invisioncommunity.com/4guides/getting-started/setting-your-default-application-r256/
6 - You will need to check any 3rd party items you have on your site are compatible