Pretty sure they already throttle the connection to 60 kB/s if they know you’re using it as a Hotspot.

I pay extra for the high speed Hotspot plan but I think it only gives me 10 or 20 GB then it throttles again.

Best is subjective. I use a Panasonic uj267 and a cheap odd enclosure. The uj267 is the same drive thats in a MacBook pro. A lot of people recommend the ASUS external drive.

I rarely use it which is kind of why I wanted a smaller footprint drive, but it reads/writes CD, DVD and bluray 4K.