1. There are a large number of templates available for TG on the internet; some individuals even collected and zipped many up into a "template megapack". If you search for that and download, you'd be able to pick one movie and quickly scroll through the templates, seeing how each template's output looks.
2. The dimensions of about.jpg do not have to be 1280x720. The Mede8er will resize any about.jpg to 1280x720 and send to the receiver/dispay device which will then convert it back to 1920x1080 (display's resolution) The actual dimensions can be anything so long as their proportion is 16x9. 1280x720, 1920x1080, 3840x2160 (4K) are all 16x9 and will scale. All my about.jpg are 1920x1080 and work just fine.
3. The top and bottom missing must be different issue. It is either because of overscan or a setting on the tv.
- what is the native tv resolution?
- how do jpgs of various resolutions show up (say, make copies of a 1920x1080 jpg, resize copies to different resoltions and rename them and check how they show through Mede8er)
Overscan setting is at the bottom of video settings; you might want to change it as the last resort if nothing else prevents the edges from being cut off.
4. I'd recommend working on one movie, making sure its files are generated to your satisfaction and then repeating that process for the entire library.
5. The output about.jpg size is part of the design of the template. Any template can be opened in ThumbGen Designer and modified. Alternately, one could pick a template that produces 1280x720 output. But, like I said above, there's no need to limit ourselves to 1280x720.