A:AnswerThe biggest difference that I can see is that the Stick plugs directly into your TV HDMI port and is basically hidden from sight. The Express needs to be placed on a surface where it is in line of sight with the Remote. It then has a cord connection from the Express to your HDMI port. Both units need to be plugged into a power source. The Stick then has a remote that does not have to be line of sight to the unit. As long as you are in the same room as the TV, you don't really have to aim the Roku Stick remote at anything to make your selections.
A:AnswerIt runs on milliwatts on a USB based plug in. It does not have a on-off on the remote. If you want it actually off you unplug it from the power source. It is "instant on" when the TV is turned on.
A:AnswerNone of the Roku devices or Chromecast devices pick up 5G internet. MOST internet companies provide you with a 5G and 2G connection for situations like these because there are devices that don't use 5G for wifi other than your desktop or laptop computer. My Roku & Chromecast have no problem with speed or download working on the 2G connection I have.