If you need to update the theme, there are 2 ways to do this:
1. WordPress: Deactivate the current theme by activating any other theme. Once the theme is not active you can delete this theme. After deleting it install the new updated theme and activate it. Don't worry you won't loose your settings,options,content, ...
2. FTP: Delete the current theme folder 'pond' in wp-content/themes/ and upload the new one.
NOTE: you won't loose your settings,options,content, ... But if you did customizations to the theme files (edit/add code), they will of course be lost because the files are replaced by the new files.
Make sure you followed the instruction from the documentaion file. Check also your spam folder.
If nothing helps make sure that your server supports a working smtp server to send emails.
Alternatively you can use the contact form 7 plugin which should work fine.
You're probably on a child theme, aren't you? Make sure you're on the main theme (not on the child theme) to install the required plugins.
The logo will display in the original size you upload it.
So, you just need to upload the logo in the size you want to show it.
Make sure that you select "Full Size" and click on "File URL" button before clicking on Insert into Post
Mobile devices doesn't support background videos, so instead, it will display the poster image you can choose in the settings.
Please follow the instruction from the documentation file. Check also your spam folder.
If nothing helps make sure that your server supports a working smtp server to send emails.
The section which are displayed on the front page are managed by the menu (Appearence > Menus). You can choose the "Go to" option for each item. Your blog page MUST be a standalone page.
Please have also a look at the documentation file and video tutorials.