My list would basically be the same as Matt's. I would definitely love to see support for background images. Any way we could eliminate the majority of the hacks we currently have to do.
Hello! Oh dear that doesn't sound like a fun week. I looked over your code and made some adjustments. Just trial and error type of stuff. Removed some of the CSS from the head and a style on the one td. Which was causing it to not show in mobile for me. I ran a few live tests on devices/clients that I have. Outlook.com, Outlook 2013, Gmail, Android and Office 365. Everything appears to be working fine. The mobile content doesn't show up on desktop, but appears on mobile.
It looked like you were following Fresh Inbox Bulletproof Solution to Hiding Mobile Content when opened in Non-Mobile Email Clients. Which is what I did too. Unfortunately I don't have Outlook 2011 to do a live test on.
Here is the code: https://litmus.com/builder/ea5a188
I'm not sure if this helps you at all, but hopefully you'll get it figured out!
I'm not familiar with the hybrid approach to responsive emails in the Gmail app. However, I do know of a little trick that will at least display the desktop version of the email properly. You can read more about it here at Fresh Inbox. Just add the code below to your email. I've always added this after the last table in my email.
<div style="display:none; white-space:nowrap; font:15px courier; color:#ffffff;">
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
You came to the right place to find information. A little while back Kevin from Litmus did a great webinar on how to code responsive emails. You can find the slides and recording here: Responsive Email 101 Webinar Q&A: HTML & CSS Basics. There are also great resources and answers to questions from the webinar on that page. I highly recommend checking it out. Hopefully that helps.
Normally I would have the 'view online' at the top, but I've seen emails with that at the bottom. I think it is fine to have it at the bottom of the email along with everything else you mentioned. I know some emails don't include the 'view online' at all. Which I think comes down to personal opinion and whether or not your subscribers are clicking on the link. We normally have a few who do and that is why we keep it in.