I don't ride ebikes myself. fatbikes are currently popular for being cheap and easy to (illegally) mod for speed.
May I suggest an "omafiets", just make sure to put the saddle high enough. It should be at your hip, you get on by standing on the paddles. They're really comfy, and you get to sit straight.
No they're not. For example, this will ruin your knees if you go any decent distance on it: