Hey Chris,
let’s deal with the size and position of the search form when the website is available online and I can see the code, otherwise it is really difficult to give precise instructions.
If you want to remove the archive and category lists from the 404 page, you’ll need to remove lines 20-21 from the 404.php template file (both lines start with div id=”error-archives”).
You can edit the meta title tag (as well as other SEO-related items) using the “SEO Options” plugin which is bundled with the theme (please see the respective admin section, “Home Title” field).
Sincerely,
Andrii / Satori Studio