That's the settings. It's the "HTML minification" we are talking about.
Don't forget that after you disable it and click "Save", you also have to restart the application from the admin, otherwise the change will not apply.
"There is no </head>, </body> or </html> tag if you view the source on https://avenue1.nop-templates.com or https://avenue2.nop-templates.com"
That's a false alert from the browser inspector due to source code minification - the html markup is minified on the Avenue demos.
I can't tell why nopCommerce minification behaves like that in browser inspectors but that has nothing to do with the theme, it's in the framework (nopCommerce) which we don't have control over. If you inspect the nopCommerce demo you will see exactly the same thing (unclosed html, head and body tags). In fact you will see the same on every nopCommerce-based website that has minification enabled. But anyway, with or without HTML minification, the <html> &<head> & <body> tags validate normally.
"Compare Avenue and Voyage demos"
You see a difference only because Avenue has HTML minification enabled, and Voyage has it disabled. If they both have it enabled you will see no difference, and if they both have it disabled you will see no difference either.
As you can see on the demo, the <head> tag is closing properly.
If it doesn't close properly on your site, you have to check any modifications you have made and find out what's wrong.
flimflap, yes, you are right, thanks for reporting it. It is now fixed, so you can update your theme (version 4.5 only), or you can change it manually in your Footer template file if you prefer (Themes\Emporium\Views\Shared\Components\Footer\Default.cshtml)
Unfortunately we were not able to reproduce your issue.
I tested various products with Tier Price enabled in Pacific 4.4 and they work as expected - I can add them to the cart from anywhere, including from carousels on Home Page.
If you are still having that issue please start a support ticket and provide us with admin access to your site so we can log in and inspect what's going on.
Avenue theme is not using images for icons, they are implemented as vector shapes coming from a font file.
You can't edit the font file, but if you are familiar with CSS you can override the default code for that specific icon and refer some new image icon that you can put into the theme "img" folder.