The mobile apps are changing significantly to accommodate the new business model and additional content types, so the Support Program will not be emphasized there in the near future. On the bright side, the vast majority of support comes from people on desktops (i.e. Windows, Mac, etc.) and not mobile users on the web or apps.
Notifications will not be included immediately, but will be added in the future when we are able!
We considered this too and realize it's less than ideal. The top cover banners were really intended as background images to introduce a bit of personalized color, style, etc., not really as a place to include detailed text or messages. However, without building a new feature or making other significant changes, adding a link to the top was the most available and visible option.
There's not really a "safe" area, as the image keeps zooming/cropping as the window size increases (i.e. if you stretch the window enough or go full screen on a large monitor, the image will continue to stretch to fit). In general the guideline is to make any important content stay within the width of the content area below... in other words, within the 940px in the center of the banner. Likewise, content is safest near the vertical center.
These will unfortunately be going away at the end of November (along with the Support buttons and other TSP features) as CK mentioned above.
However, you can of course add additional links in your series and episode descriptions if you like.