fix wordpress errors & make site responsive

I did a wordpress update and something happened to create a few errors. #1. It's not a permalink issue, as i re-saved my permalink. When i'm in wp-admin and click 'pages' or 'settings and menu' i'll get a 404 error. Then if i wait a minute, it'll work. #2. When i'm editing a page, and using visual editor, i click on a function. Sometimes it won't load properly. If it does load and i click 'save' , sometimes the window won't close. #3. When I update a page and re-load the page on the front end, the formatting will be all off. Then I need to click the home page and back to the recently updated page and it will be fixed. Very strange. #4. The video at the top of my page plays on iMac. But not on my firefox linux computer. Android looks horrible and doesn't load the content properly. Also some of the icon's don't load but then they do load on other devices. So I need it to be responsive on all devices. Some youtube video's load but others don't on other devices. Could be a conflicting plugin or something. I don't need any web work other than fixing these errors.