There are two site configuration issues which can be fixed quickly without any fix from the theme side –
1) Looks like the font-awesome plugin is loaded. You will need to unload it since it is conflicting it with the icomoon icon fonts bundled with the theme. The icon for the mobile menu should show up then.
If you really want to have font-awesome loaded, you need to modify the file header.php at line number 62 from
echo '<i class="icon-list-3"></i> ';
to
echo '<i class="icon-list"></i> ';
BTW, here are icomoon icons bundled with the theme (in case you loaded font-awesome because you could not find information about existing icomoon icons) –
http://hothanded.com/wp-content/themes/appdev/images/icons/icomoon/sprites/index.html
When font-awesome loads, it blocks out many of these icons since it takes over as font-family for these icons from icomoon.
2) You will need to set the retina logo in the Site Logo tab in the options panel. The logo will then show up on retina displays like iPhone/iPad. No need to make the custom fix suggested by Frank then (thank you Frank BTW for the quick help, truly appreciate it).
Hope this helps.