Marwan's tail is twice as long as his height, which is 6 feet. It's also prehensile.
Marwan's ears should be drawn so that they're long enough that the tips can touch his knees while he's standing up. (If you want exact measurements, each ear is 1.8 feet long.) They're floppy and should never appear rigid. And they grew from where human ears logically grew from his head.