60 miles, do you have a tower? You might want to start your research at antennaweb.org.
What made you decide to cut the cord now? Because the Fire TV doesn't do much of anything that a Roku couldn't already do. Just hope you carefully considered what you are giving up by cord cutting. Timing seems a little hype driven.
UMR on HDR vs 4K: The benefit of greater saturation and luminance capability is...not very evident in all images unlike more pixels which can be seen in every scene.