I don't think it would be 81, but you are correct that it's wrong. Shouldn't be 16 because my TV only displays up to 720p, not 1080p. Although it is a 16:9 TV (not 64:27 like it shows under #81). Also, my TV frequency isn't 30Hz, unless I'm missing something.
you've fixed it now so i guess this is irrelevant but yes, you'd need to use hdmi_group=2 for 81 - it doesn't seem to be supported under 1. but yes, @mitu 's suggestion would get show you the complete list of supported modes. given that it's less than 4k, i would always want to be running in the native panel resolution so you don't get scaling artefacts.
i assume now you've taken out hdmi_safe you can safely take out any hard coded modes and it should hopefully choose 1366x768 by default.
While SD cards are awesome for size/weight/etc., how much of a speed advantage would using an external hdd be? I can't imagine an ssd adding any value over a simple 2.0/3.0 mechanical drive being that the transfer rate is bottlenecked by the shared usb 2.0 bus which apparently is divided up by the all ports and the sd card reader. Is a top of the line sd card just as good as an external hard drive or are there any advantages?