Hi! I'm pretty sure television type flat panels will only accept horizontal-to-vertical ratio content anyway. Some computer screens are more flexible. For television, it means you must produce your content as minus 90 degrees, i.e. 'lying down'. Then, when you turn the screen on its short edge (plus 90 degrees) it will look right.
In AE, I'd produce the final content as a composition turned -90 degrees.
For transparency, use +32 bit color export.
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